Measles, Mumps, Rubella and Varicella virus vaccine live(Merck & Co., Inc.)

Fourth-Quarter Worldwide Sales Were $16.4 Billion (5% Growth; 4% Growth ex-FX) Fourth-Quarter GAAP EPS Was $1.19; Non-GAAP EPS Was $2.04; GAAP and Non-GAAP EPS Include a Charge of $0.05 per Share for the Acquisition of MK-8690 Sole Global Rights Full-Year Worldwide Sales Were $65.0 Billion (1% Growth; 2% Growth ex-FX) KEYTRUDA/KEYTRUDA QLEX Sales Were $31.7 Billion (7% Growth Both Nominally and ex-FX); Includes KEYTRUDA QLEX Sales of $40 Million WINREVAIR Sales Were $1.4 Billion CAPVAXIVE Sales Were $759 Million GARDASIL/GARDASIL 9 Sales Were $5.2 Billion (39% Decline Both Nominally and ex-FX) Animal Health Sales Were $6.4 Billion (8% Growth; 9% Growth ex-FX) KEYTRUDA/KEYTRUDA QLEX Sales Were $31.7 Billion (7% Growth Both Nominally and ex-FX); Includes KEYTRUDA QLEX Sales of $40 Million WINREVAIR Sales Were $1.4 Billion CAPVAXIVE Sales Were $759 Million GARDASIL/GARDASIL 9 Sales Were $5.2 Billion (39% Decline Both Nominally and ex-FX) Animal Health Sales Were $6.4 Billion (8% Growth; 9% Growth ex-FX) Full-Year 2025 GAAP EPS Was $7.28; Non-GAAP EPS Was $8.98; GAAP and Non-GAAP EPS Include Charges of $0.20 per Share Related to Certain Business Development Transactions Announced Positive Late-Stage Trial Results From 18 Phase 3 Trials in 2025 Augmented Pipeline and Portfolio Through Acquisitions of Verona Pharma and Cidara Therapeutics and License Agreement With Hengrui Pharma In the Fourth Quarter Received FDA Commissioner’s National Priority Vouchers for Enlicitide and Sacituzumab Tirumotecan (Sac-TMT), Providing an Opportunity To Expedite Potential FDA Review Timelines for These Phase 3 Candidates Presented Positive Results From Phase 3 CORALreef Lipids and HeFH Trials Demonstrating Enlicitide Significantly Reduced LDL-C in Adults Reached Agreement With U.S. Government To Expand Access to Medicines and Lower Costs for Americans Received FDA Commissioner’s National Priority Vouchers for Enlicitide and Sacituzumab Tirumotecan (Sac-TMT), Providing an Opportunity To Expedite Potential FDA Review Timelines for These Phase 3 Candidates Presented Positive Results From Phase 3 CORALreef Lipids and HeFH Trials Demonstrating Enlicitide Significantly Reduced LDL-C in Adults Reached Agreement With U.S. Government To Expand Access to Medicines and Lower Costs for Americans Full-Year 2026 Financial Outlook Anticipates Worldwide Sales To Be Between $65.5 Billion and $67.0 Billion Expects Non-GAAP EPS To Be Between $5.00 and $5.15; Outlook Reflects a One-Time Charge of Approximately $3.65 per Share for the Acquisition of Cidara Anticipates Worldwide Sales To Be Between $65.5 Billion and $67.0 Billion Expects Non-GAAP EPS To Be Between $5.00 and $5.15; Outlook Reflects a One-Time Charge of Approximately $3.65 per Share for the Acquisition of Cidara RAHWAY, N.J.--(BUSINESS WIRE)--Merck & Co., Inc., Rahway, N.J., USA (NYSE: MRK), known as MSD outside the United States and Canada, today announced financial results for the fourth quarter and full year of 2025. "In 2025, we continued to advance leading-edge science to deliver transformative medicines and vaccines that are improving health outcomes for patients around the world,” said Robert M. Davis, chairman and chief executive officer. "Our business benefited from demand for our innovative portfolio, including for KEYTRUDA, increasing contributions from new launches in cardiometabolic and respiratory as well as vaccines, and strong performance of Animal Health. The transformation of our portfolio, bolstered by the acquisitions of Verona Pharma and Cidara Therapeutics, is well underway, and momentum is building as we continue to execute on our strategy. Our progress positions us to continue delivering on our purpose for patients and creating durable value for shareholders.” Financial Summary $ in millions, except EPS amounts Fourth Quarter Year Ended 2025 2024 Change Change Ex-Exchange Dec. 31, 2025 Dec. 31, 2024 Change Change Ex-Exchange Sales $16,400 $15,624 5% 4% $65,011 $64,168 1% 2% GAAP net income1 2,963 3,743 -21% -20% 18,254 17,117 7% 9% Non-GAAP net income that excludes certain items1,2* 5,088 4,372 16% 17% 22,513 19,444 16% 18% GAAP EPS 1.19 1.48 -20% -18% 7.28 6.74 8% 10% Non-GAAP EPS that excludes certain items2* 2.04 1.72 19% 19% 8.98 7.65 17% 19% *Refer to table on page 9. Generally Accepted Accounting Principles (GAAP) earnings per share (EPS) assuming dilution was $1.19 for the fourth quarter and $7.28 for the full year of 2025. Non-GAAP EPS was $2.04 for the fourth quarter and $8.98 for the full year of 2025. GAAP and non-GAAP EPS in the fourth quarter of 2025 include a charge of $0.05 per share related to an agreement with Dr. Falk Pharma GmbH (Falk) pursuant to which the Company secured the sole global rights to MK-8690. GAAP and non-GAAP EPS in the fourth quarter of 2024 include a charge of $0.23 per share related to the execution of licensing agreements with LaNova Medicines Ltd. (acquired by Sino Pharmaceutical Limited) and Hansoh Pharma. GAAP and non-GAAP EPS for the full years of 2025 and 2024 include charges of $0.20 and $1.28 per share, respectively, related to certain licensing agreements and asset acquisitions. Non-GAAP EPS excludes acquisition- and divestiture-related costs, costs related to restructuring programs, and income and losses from investments in equity securities. Non-GAAP EPS in 2025 also excludes a net tax benefit, which reflects a net benefit related to favorable audit reserve adjustments. Non-GAAP EPS in the fourth quarter and full year of 2024 also exclude a benefit due to a reduction in reserves for unrecognized income tax benefits resulting from the expiration of the statute of limitations for assessments related to certain federal tax return years. Fourth-Quarter Sales Performance The following table reflects sales of the Company’s top products and significant performance drivers. Fourth Quarter $ in millions 2025 2024 Change Change Ex-Exchange Commentary Total Sales $16,400 $15,624 5% 4% Pharmaceutical 14,843 14,042 6% 4% Increase primarily driven by growth in oncology as well as cardiometabolic and respiratory, partially offset by a decline in vaccines. KEYTRUDA/ KEYTRUDA QLEX 8,372 7,836 7% 5% Growth driven by strong global uptake in earlier-stage indications, including triple-negative breast cancer (TNBC), non-small cell lung cancer (NSCLC), renal cell carcinoma, cervical and head and neck cancers, as well as continued global demand in metastatic indications, including urothelial, gastric and endometrial cancers. Sales growth was partially offset by timing of purchases in the U.S. Sales of KEYTRUDA QLEX were $35 million. GARDASIL/ GARDASIL 9 1,031 1,550 -34% -35% Decline primarily due to lower demand in China, as well as lower sales in Japan following the national catch-up immunization program, partially offset by higher sales in the U.S. and timing in certain international markets. PROQUAD, M-M-R II and VARIVAX 619 594 4% 3% Increase primarily reflects higher sales of PROQUAD, which largely resulted from both the replenishment of doses borrowed from the U.S. Centers for Disease Control and Prevention Pediatric Vaccine Stockpile and from higher demand in Europe, partially offset by lower demand for M-M-R II in certain international markets and lower demand for VARIVAX in the U.S. JANUVIA/JANUMET 501 487 3% 3% Growth driven by higher net pricing in the U.S., partially offset by lower demand in China as well as in most other international markets due to generic competition. BRIDION 499 449 11% 11% Growth primarily due to higher demand and net pricing in the U.S., partially offset by lower demand in several international markets due to ongoing generic competition. WINREVAIR 467 200 133% 133% Growth primarily reflects continued uptake in the U.S. and early launch uptake in certain international markets, partially offset by lower net pricing in the U.S. largely due to Medicare Part D redesign. Lynparza* 389 365 7% 4% Growth primarily due to higher demand in several international markets. CAPVAXIVE 279 50 N/M N/M Growth largely due to continued uptake in the U.S. PREVYMIS 275 215 28% 26% Increase primarily due to higher demand in the U.S. as well as in most international markets, reflecting in part the launch of new indications. Lenvima* 272 255 7% 6% Increase due to higher sales in the U.S., primarily reflecting higher demand, partially offset by lower pricing. WELIREG 220 160 37% 37% Growth primarily due to higher demand in the U.S. and continued launch uptake in several international markets, partially offset by lower net pricing in the U.S. OHTUVAYRE 178 - - - Represents sales following the Company's Oct. 7, 2025 acquisition of Verona Pharma plc (Verona Pharma). Animal Health 1,505 1,397 8% 6% Growth primarily due to higher demand of livestock products. Livestock 987 889 11% 9% Growth primarily driven by higher demand across all species, as well as improved supply and new product launches. Companion Animal 518 508 2% 0% Growth from new product launches was partially offset by lower demand for other products in portfolio, reflecting a reduction in veterinary visits. Sales of BRAVECTO line of products were $222 million and $209 million in current and prior-year quarters, respectively, which represents an increase of 6%, or 5% excluding impact of foreign exchange. Other Revenues** 52 185 -71% -15% Decline primarily due to unfavorable impact of revenue-hedging activities and lower revenue from third-party manufacturing arrangements. *Alliance revenue for this product represents the Company’s share of profits, which are product sales net of cost of sales and commercialization costs. **Other revenues are comprised primarily of revenues from third-party manufacturing arrangements and miscellaneous corporate revenues, including revenue-hedging activities. N/M - Not meaningful. Full-Year Sales Performance The following table reflects sales of the Company’s top products and significant performance drivers. Year Ended $ in millions Dec. 31, 2025 Dec. 31, 2024 Change Change Ex-Exchange Total Sales $65,011 $64,168 1% 2% Pharmaceutical 58,142 57,400 1% 1% KEYTRUDA/KEYTRUDA QLEX 31,680 29,482 7% 7% GARDASIL/GARDASIL 9 5,233 8,583 -39% -39% JANUVIA/JANUMET 2,544 2,268 12% 13% PROQUAD, M-M-R II and VARIVAX 2,451 2,485 -1% -2% BRIDION 1,841 1,764 4% 4% Lynparza* 1,450 1,311 11% 10% WINREVAIR 1,443 419 N/M N/M Lenvima* 1,053 1,010 4% 4% PREVYMIS 978 785 25% 23% VAXNEUVANCE 825 808 2% 1% CAPVAXIVE 759 97 N/M N/M WELIREG 716 509 41% 41% ROTATEQ 673 711 -5% -5% Reblozyl* 525 371 41% 41% LAGEVRIO 380 964 -61% -61% Simponi** - 543 -100% -100% Animal Health 6,354 5,877 8% 9% Livestock 3,896 3,462 13% 14% Companion Animal 2,458 2,415 2% 2% Other Revenues*** 515 891 -42% -6% *Alliance revenue for Lynparza and Lenvima represent the Company’s share of profits, which are product sales net of cost of sales and commercialization costs. Alliance revenue for Reblozyl represents royalties. **Marketing rights in former territories of the Company reverted to Johnson & Johnson on Oct. 1, 2024. ***Other revenues are comprised primarily of revenues from third-party manufacturing arrangements and miscellaneous corporate revenues, including revenue-hedging activities. N/M - Not meaningful. In addition, Koselugo alliance revenue was $436 million for the full year of 2025 compared with $170 million for the full year of 2024. The increase was due to an amendment to the collaboration agreement with AstraZeneca in 2025, which discontinued the provisions whereby the Company shared revenue and costs with AstraZeneca, and revised the payment structure, resulting in the Company’s recognition of a $150 million upfront payment and $175 million of regulatory milestones. Full-year 2025 Pharmaceutical sales were $58.1 billion, representing growth of 1% both nominally and excluding the impact of foreign exchange. Sales growth was primarily driven by higher sales in oncology, particularly KEYTRUDA and WELIREG, as well as increased alliance revenue from Koselugo (resulting from the amendment to the collaboration agreement noted above), Reblozyl and Lynparza. Also contributing to sales growth were higher sales in the cardiometabolic and respiratory franchise largely attributable to the ongoing launch of WINREVAIR, as well as the inclusion of OHTUVAYRE sales resulting from the acquisition of Verona Pharma, which closed on Oct. 7, 2025. Growth in the diabetes franchise, largely attributable to higher net pricing of JANUVIA in the U.S., also contributed to sales growth. Sales growth in 2025 was partially offset by lower sales in the vaccines franchise reflecting lower sales of GARDASIL/GARDASIL 9, which were offset in part by the ongoing launch of CAPVAXIVE and the U.S. launch of ENFLONSIA. Lower sales in the immunology franchise (due to the return of the marketing rights for Simponi and Remicade in former Company territories to Johnson & Johnson on Oct. 1, 2024) and lower sales in the virology franchise (largely attributable to LAGEVRIO) also offset Pharmaceutical sales growth in 2025. Full-year 2025 Animal Health sales were $6.4 billion, representing growth of 8%, or 9% excluding the impact of foreign exchange. Sales growth was primarily driven by the performance of Livestock products across all species and new product launches in Companion Animal. Sales of the BRAVECTO line of products were $1.1 billion in 2025, representing growth of 1% both nominally and excluding the impact of foreign exchange. Fourth-Quarter and Full-Year Expense and Related Information The table below presents selected expense information. $ in millions GAAP Acquisition- and Divestiture- Related Costs3 Restructuring Costs (Income) Loss From Investments in Equity Securities Non- GAAP2 Fourth Quarter 2025 Cost of sales $5,551 $1,054 $1,173 $- $3,324 Selling, general and administrative 2,898 48 2 - 2,848 Research and development 3,886 5 (111) - 3,992 Restructuring costs 213 - 213 - - Other (income) expense, net 432 - - 206 226 Fourth Quarter 2024 Cost of sales $3,828 $701 $121 $- $3,006 Selling, general and administrative 2,864 29 16 - 2,819 Research and development 4,585 12 (1) - 4,574 Restructuring costs 51 - 51 - - Other (income) expense, net 126 (31) - 152 5 $ in millions GAAP Acquisition- and Divestiture- Related Costs3 Restructuring Costs (Income) Loss From Investments in Equity Securities Non- GAAP2 Year Ended Dec. 31, 2025 Cost of sales $16,382 $2,871 $1,484 $- $12,027 Selling, general and administrative 10,733 120 3 - 10,610 Research and development 15,789 19 175 - 15,595 Restructuring costs 889 - 889 - - Other (income) expense, net 151 (3) - (306) 460 Year Ended Dec. 31, 2024 Cost of sales $15,193 $2,409 $495 $- $12,289 Selling, general and administrative 10,816 117 83 - 10,616 Research and development 17,938 72 1 - 17,865 Restructuring costs 309 - 309 - - Other (income) expense, net (24) (79) - 45 10 GAAP Expense, EPS and Related Information Gross margin was 66.2% for the fourth quarter of 2025 compared with 75.5% for the fourth quarter of 2024. Gross margin was 74.8% for the full year of 2025 compared with 76.3% for the full year of 2024. The gross margin decline in both periods was primarily due to the unfavorable impacts of higher restructuring costs (primarily related to the accelerated depreciation of manufacturing lines at two sites under the 2025 Restructuring Program), inventory write-offs and amortization of intangible assets, as well as the recognition of inventory fair value step-up related to the Verona Pharma acquisition, partially offset by the favorable impact of product mix. Selling, general and administrative (SG&A) expenses were $2.9 billion in the fourth quarter of 2025, an increase of 1% compared with the fourth quarter of 2024. The increase was primarily due to higher administrative costs, partially offset by lower promotional costs. Full-year 2025 SG&A expenses were $10.7 billion, a decrease of 1% compared with the full year of 2024. The decrease was primarily due to lower restructuring and promotional costs, partially offset by increased administrative costs. Research and development (R&D) expenses were $3.9 billion in the fourth quarter of 2025, a decrease of 15% compared with the fourth quarter of 2024. The decrease was primarily due to lower charges for business development activity and a reduction to estimated contractual termination costs associated with restructuring actions, partially offset by higher clinical development costs. R&D expenses were $15.8 billion for the full year of 2025, a decrease of 12% compared with the full year of 2024. The decrease was primarily due to lower charges for business development activity, partially offset by higher clinical development spending and higher restructuring costs. Other (income) expense, net, was $432 million of expense in the fourth quarter of 2025 compared with $126 million of expense in the fourth quarter of 2024 primarily due to higher net interest expense, higher foreign exchange losses and increased net losses from investments in equity securities. Other (income) expense, net, was $151 million of expense in the full year of 2025 compared with $24 million of income in the full year of 2024. The unfavorable year-over-year change primarily reflects $170 million of income in 2024 related to the expansion of an existing development and commercialization agreement with Daiichi Sankyo, as well as higher net interest expense and higher foreign exchange losses in 2025, partially offset by higher net income from investments in equity securities in 2025. The effective tax rate was 13.4% for the fourth quarter of 2025 and 13.3% for the full year of 2025. GAAP EPS was $1.19 for the fourth quarter of 2025 compared with $1.48 for the fourth quarter of 2024. The decrease was primarily driven by higher restructuring costs and amortization of intangible assets, partially offset by favorability from lower charges for business development transactions, as well as operational strength in the business driven in part by the benefits of the previously announced multiyear optimization initiative. GAAP EPS was $7.28 for the full year of 2025 compared with $6.74 for the full year of 2024. The increase was primarily driven by favorability from lower charges for business development transactions and operational strength in the business, partially offset by higher restructuring costs and amortization of intangible assets. Non-GAAP Expense, EPS and Related Information Non-GAAP gross margin was 79.7% for the fourth quarter of 2025 compared with 80.8% for the fourth quarter of 2024. The decrease was primarily due to higher inventory write-offs, partially offset by the favorable impact of product mix. Non-GAAP gross margin was 81.5% for the full year of 2025 compared with 80.8% for the full year of 2024. The increase was primarily due to the favorable impact of product mix, partially offset by higher inventory write-offs. Non-GAAP SG&A expenses were $2.8 billion in the fourth quarter of 2025, an increase of 1% compared with the fourth quarter of 2024. The increase was primarily due to higher administrative costs, partially offset by lower promotional costs. Non-GAAP SG&A expenses were $10.6 billion for the full year of 2025, flat compared with the full year of 2024 as lower promotional costs were largely offset by higher administrative costs. Non-GAAP R&D expenses were $4.0 billion in the fourth quarter of 2025, a decrease of 13% compared with the fourth quarter of 2024. Non-GAAP R&D expenses were $15.6 billion for the full year of 2025, a decrease of 13% compared with the full year of 2024. The decrease in both periods was primarily due to lower charges for business development activity, partially offset by higher clinical development costs. Non-GAAP other (income) expense, net, was $226 million of expense in the fourth quarter of 2025 compared with $5 million of expense in the fourth quarter of 2024 primarily due to higher net interest expense and higher foreign exchange losses. Non-GAAP other (income) expense, net, was $460 million of expense in the full year of 2025 compared with $10 million of expense in the full year of 2024. The unfavorable year-over-year change primarily reflects $170 million of income in 2024 related to the expansion of an existing development and commercialization agreement with Daiichi Sankyo, as well as higher net interest expense and higher foreign exchange losses in 2025. The non-GAAP effective tax rate was 15.4% for the fourth quarter of 2025 and 14.4% for the full year of 2025. Non-GAAP EPS was $2.04 for the fourth quarter of 2025 compared with $1.72 for the fourth quarter of 2024. Non-GAAP EPS was $8.98 for the full year of 2025 compared with $7.65 for the full year of 2024. The increase in both periods was primarily driven by favorability from lower charges for business development transactions, as well as operational strength in the business driven in part by the benefits of the previously announced multiyear optimization initiative. A reconciliation of GAAP to non-GAAP net income and EPS is provided in the table that follows. Fourth Quarter Year Ended $ in millions, except EPS amounts 2025 2024 Dec. 31, 2025 Dec. 31, 2024 EPS GAAP EPS $1.19 $1.48 $7.28 $6.74 Difference 0.85 0.24 1.70 0.91 Non-GAAP EPS that excludes items listed below2 $2.04 $1.72 $8.98 $7.65 Net Income GAAP net income1 $2,963 $3,743 $18,254 $17,117 Difference 2,125 629 4,259 2,327 Non-GAAP net income that excludes items listed below1,2 $5,088 $4,372 $22,513 $19,444 Excluded Items: Acquisition- and divestiture-related costs3 $1,107 $711 $3,007 $2,519 Restructuring costs 1,277 187 2,551 888 Loss (income) from investments in equity securities 206 152 (306) 45 Decrease to net income before taxes 2,590 1,050 5,252 3,452 Estimated income tax (benefit) expense4 (465) (421) (993) (1,125) Decrease to net income $2,125 $629 $4,259 $2,327 Pipeline and Portfolio Highlights In 2025, the Company announced positive late-stage trial results from 18 Phase 3 trials and began enrolling patients in 21 new Phase 3 studies evaluating multiple indications and therapeutic areas, with approximately 80 Phase 3 studies currently underway. Throughout the fourth quarter, the Company made important progress to advance its broad, diverse pipeline, meeting significant regulatory and clinical milestones. Oncology: U.S. Food and Drug Administration (FDA) approved KEYTRUDA and KEYTRUDA QLEX, each in combination with Padcev, for the perioperative treatment of adult patients with muscle-invasive bladder cancer (MIBC) who are ineligible for cisplatin-based chemotherapy based on Phase 3 KEYNOTE-905 trial. Approvals represent the first PD-1 inhibitor plus antibody-drug conjugate (ADC) regimens for this patient population. FDA awarded a priority review voucher under the Commissioner’s National Priority Voucher (CNPV) pilot program for sac-TMT, an investigational anti-TROP2 ADC being developed in collaboration with Kelun-Biotech. European Commission (EC) approved the subcutaneous route of administration and new pharmaceutical formulation of KEYTRUDA for use across all KEYTRUDA indications for adult patients in Europe. FDA accepted two supplemental Biologics License Applications (sBLAs) for KEYTRUDA and KEYTRUDA QLEX, each with Trodelvy, for the first-line treatment of certain patients with PD-L1+ inoperable (unresectable) locally advanced or metastatic TNBC based on Phase 3 KEYNOTE-D19/ASCENT-04 trial. FDA set Prescription Drug User Fee Act (PDUFA) dates in the second half of 2026 for these applications. Announced positive topline results from Phase 3 KEYNOTE-B15 trial in patients with MIBC who are eligible for cisplatin-based chemotherapy showing KEYTRUDA plus Padcev significantly improved event-free survival (EFS), overall survival (OS) and pathologic complete response (pCR) rates versus neoadjuvant chemotherapy and surgery when given before and after surgery. In collaboration with Moderna, Inc. (Moderna), announced median five-year follow-up data from Phase 2b KEYNOTE-942/mRNA-4157-P201 study for intismeran autogene, an investigational mRNA-based individualized neoantigen therapy, in combination with KEYTRUDA in patients with high-risk melanoma (stage III/IV) following complete resection. U.S. Food and Drug Administration (FDA) approved KEYTRUDA and KEYTRUDA QLEX, each in combination with Padcev, for the perioperative treatment of adult patients with muscle-invasive bladder cancer (MIBC) who are ineligible for cisplatin-based chemotherapy based on Phase 3 KEYNOTE-905 trial. Approvals represent the first PD-1 inhibitor plus antibody-drug conjugate (ADC) regimens for this patient population. FDA awarded a priority review voucher under the Commissioner’s National Priority Voucher (CNPV) pilot program for sac-TMT, an investigational anti-TROP2 ADC being developed in collaboration with Kelun-Biotech. European Commission (EC) approved the subcutaneous route of administration and new pharmaceutical formulation of KEYTRUDA for use across all KEYTRUDA indications for adult patients in Europe. FDA accepted two supplemental Biologics License Applications (sBLAs) for KEYTRUDA and KEYTRUDA QLEX, each with Trodelvy, for the first-line treatment of certain patients with PD-L1+ inoperable (unresectable) locally advanced or metastatic TNBC based on Phase 3 KEYNOTE-D19/ASCENT-04 trial. FDA set Prescription Drug User Fee Act (PDUFA) dates in the second half of 2026 for these applications. Announced positive topline results from Phase 3 KEYNOTE-B15 trial in patients with MIBC who are eligible for cisplatin-based chemotherapy showing KEYTRUDA plus Padcev significantly improved event-free survival (EFS), overall survival (OS) and pathologic complete response (pCR) rates versus neoadjuvant chemotherapy and surgery when given before and after surgery. In collaboration with Moderna, Inc. (Moderna), announced median five-year follow-up data from Phase 2b KEYNOTE-942/mRNA-4157-P201 study for intismeran autogene, an investigational mRNA-based individualized neoantigen therapy, in combination with KEYTRUDA in patients with high-risk melanoma (stage III/IV) following complete resection. Infectious Diseases: Announced positive topline results from the Phase 3 trial of the investigational, once-daily, oral, two-drug, single-tablet regimen of doravirine/islatravir (DOR/ISL) for the treatment of adults with HIV-1 infection who had not previously received antiretroviral treatment (treatment-naïve). Announced positive topline results from the Phase 3 trial of the investigational, once-daily, oral, two-drug, single-tablet regimen of doravirine/islatravir (DOR/ISL) for the treatment of adults with HIV-1 infection who had not previously received antiretroviral treatment (treatment-naïve). Cardiometabolic and Respiratory: Presented new data at the American Heart Association Scientific Sessions 2025, including results from the Phase 3 CORALreef Lipids and heterozygous familial hypercholesterolemia (HeFH) trials, demonstrating that enlicitide decanoate, an investigational, oral proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor being evaluated for the treatment of adults with hypercholesterolemia, significantly reduced low-density lipoprotein cholesterol (LDL-C) with a safety profile comparable to placebo. FDA awarded a priority review voucher under the CNPV pilot program for enlicitide decanoate. In January 2026, EC approved an expanded indication for WINREVAIR, in combination with other pulmonary arterial hypertension (PAH) therapies, for the treatment of PAH (Group 1 pulmonary hypertension) in adult patients with World Health Organization (WHO) Functional Class II, III and IV based on Phase 3 ZENITH trial. In February 2026, FDA accepted a new sBLA for WINREVAIR seeking approval to update the U.S. product label based on Phase 3 HYPERION trial. FDA set PDUFA date of September 21, 2026. Announced that Phase 2, proof-of-concept CADENCE study evaluating WINREVAIR in adults for the treatment of combined post- and precapillary pulmonary hypertension (CpcPH) due to heart failure with preserved ejection fraction (HFpEF) met its primary endpoint. Presented new data at the American Heart Association Scientific Sessions 2025, including results from the Phase 3 CORALreef Lipids and heterozygous familial hypercholesterolemia (HeFH) trials, demonstrating that enlicitide decanoate, an investigational, oral proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor being evaluated for the treatment of adults with hypercholesterolemia, significantly reduced low-density lipoprotein cholesterol (LDL-C) with a safety profile comparable to placebo. FDA awarded a priority review voucher under the CNPV pilot program for enlicitide decanoate. In January 2026, EC approved an expanded indication for WINREVAIR, in combination with other pulmonary arterial hypertension (PAH) therapies, for the treatment of PAH (Group 1 pulmonary hypertension) in adult patients with World Health Organization (WHO) Functional Class II, III and IV based on Phase 3 ZENITH trial. In February 2026, FDA accepted a new sBLA for WINREVAIR seeking approval to update the U.S. product label based on Phase 3 HYPERION trial. FDA set PDUFA date of September 21, 2026. Announced that Phase 2, proof-of-concept CADENCE study evaluating WINREVAIR in adults for the treatment of combined post- and precapillary pulmonary hypertension (CpcPH) due to heart failure with preserved ejection fraction (HFpEF) met its primary endpoint. Business Development: In 2026, completed acquisition of Cidara Therapeutics, Inc. (Cidara) for a total transaction value of approximately $9.2 billion. Added MK-1406 (formerly CD388), an investigational long-acting, strain-agnostic antiviral agent designed to prevent influenza infection in individuals at higher risk of complications, to the Company’s portfolio. MK-1406 is currently being evaluated in the Phase 3 ANCHOR study. Entered into strategic financing agreement with Blackstone Life Sciences to partially fund the development of sac-TMT in 2026. Entered into an agreement with Falk for certain development and commercialization rights to MK-8690, an investigational anti-CD30 ligand monoclonal antibody. In 2026, completed acquisition of Cidara Therapeutics, Inc. (Cidara) for a total transaction value of approximately $9.2 billion. Added MK-1406 (formerly CD388), an investigational long-acting, strain-agnostic antiviral agent designed to prevent influenza infection in individuals at higher risk of complications, to the Company’s portfolio. MK-1406 is currently being evaluated in the Phase 3 ANCHOR study. Entered into strategic financing agreement with Blackstone Life Sciences to partially fund the development of sac-TMT in 2026. Entered into an agreement with Falk for certain development and commercialization rights to MK-8690, an investigational anti-CD30 ligand monoclonal antibody. Notable recent news releases on the Company’s pipeline and portfolio are provided in the table that follows. Visit the News Releases section of the Company’s website to read the releases.* Oncology FDA Approved KEYTRUDA and KEYTRUDA QLEX, Each With Padcev, as Perioperative Treatment for Adults With Cisplatin-Ineligible MIBC; Based on Results From Phase 3 KEYNOTE-905 Trial EC Approved Subcutaneous Administration of KEYTRUDA for All Adult Indications Approved in EU; Based on Results From Phase 3 3475A-D77 Trial KEYTRUDA Plus Padcev Significantly Improved EFS, OS and pCR Rates for Cisplatin-Eligible Patients With MIBC When Given Before and After Surgery; Based on Results From Phase 3 KEYNOTE-B15 Trial The Company and Moderna Announced 5-Year Data for Intismeran Autogene in Combination With KEYTRUDA Demonstrated Sustained Improvement in the Primary Endpoint of Recurrence-Free Survival in Patients With High-Risk Stage III/IV Melanoma Following Complete Resection; Based on Follow-up Analysis From Phase 2b KEYNOTE-942/mRNA-4157-P201 Trial The Company Initiated Phase 3 KANDLELIT-007 Trial Evaluating Calderasib (MK-1084), an Investigational Oral KRAS G12C Inhibitor, in Combination With KEYTRUDA QLEX in Certain Patients With Advanced NSCLC The Company Presented Data at the American Society of Hematology Annual Meeting 2025 That Showcased Continued Advancements in Hematology Pipeline and Novel Therapeutic Approaches Vaccines and Infectious Diseases The Company Announced Positive Topline Results From Pivotal Phase 3 Trial Evaluating Investigational, Once-Daily, Oral, Two-Drug, Single-Tablet Regimen of DOR/ISL in Treatment-Naïve Adults With HIV-1 Infection Cardiometabolic and Respiratory Enlicitide Decanoate Significantly Reduced LDL-C in Phase 3 CORALreef Lipids Trial Enlicitide Decanoate Significantly Reduced LDL-C in Adults With HeFH in Phase 3 CORALreef HeFH Trial WINREVAIR Met Primary Endpoint in Phase 2, Proof-Of-Concept CADENCE Study in Adults With CpcPH Due to HFpEF Neuroscience The Company Showcased Data for Alzheimer’s Disease Candidates MK-2214 and MK-1167 at Clinical Trials on Alzheimer’s Disease 2025 Animal Health FDA Conditionally Approved EXZOLT CATTLE-CA1 for Prevention and Treatment of New World Screwworm (Cochliomyia Hominivorax) Larvae (Myiasis) *References to the Company’s name in the above news release titles have been modified for the purpose of this announcement. U.S. Government Agreement The Company reached an agreement with the U.S. government that is intended to lower medicine costs for Americans. This agreement enables the Company to continue its long-standing commitment to advancing breakthrough scientific discoveries for patients and helps ensure Americans can access the medicines they need at lower costs. The voluntary agreement addresses all four components of the President’s July letter. Under the agreement, among other things, the Company plans to provide key products through a direct-to-patient program at affordable prices for eligible patients in the U.S. In addition, the Company reached an understanding with the U.S. Department of Commerce to delay Section 232 tariffs for three years, enabling the Company to make investments in the U.S. to reshore manufacturing for American patients. The Company has committed more than $70 billion in capital and R&D spending to strengthen U.S. production and innovation. Full-Year 2026 Financial Outlook The following table summarizes the Company’s full-year financial outlook. Full Year 2026 Sales* $65.5 billion to $67.0 billion Non-GAAP Gross margin2 Approximately 82% Non-GAAP Operating expenses2** $35.9 billion to $36.9 billion Non-GAAP Other (income) expense, net2 Approximately $1.3 billion expense Non-GAAP Effective tax rate2 23.5% to 24.5% Non-GAAP EPS2*** $5.00 to $5.15 Share count (assuming dilution) Approximately 2.48 billion *The Company does not have any non-GAAP adjustments to sales. **Includes a one-time charge of approximately $9.0 billion associated with the acquisition of Cidara. Outlook does not assume any additional significant potential business development transactions. ***Includes a one-time charge of approximately $3.65 per share associated with the acquisition of Cidara. The Company has not provided a reconciliation of forward-looking non-GAAP gross margin, non-GAAP operating expenses, non-GAAP other (income) expense, net, non-GAAP effective tax rate and non-GAAP EPS to the most directly comparable GAAP measures, given it cannot predict with reasonable certainty the amounts necessary for such a reconciliation, including intangible asset impairment charges, legal settlements, and income and losses from investments in equity securities either owned directly or through ownership interests in investment funds, without unreasonable effort. These items are inherently difficult to forecast and could have a significant impact on the Company’s future GAAP results. The Company anticipates full-year 2026 sales to be between $65.5 billion and $67.0 billion, including a positive impact from foreign exchange of approximately 1% at mid-January 2026 exchange rates. The Company’s full-year non-GAAP effective income tax rate is expected to be between 23.5% and 24.5% including the impact of the non-tax deductible one-time charge for the acquisition of Cidara. The Company expects full-year 2026 non-GAAP EPS to be between $5.00 and $5.15, including a positive impact from foreign exchange of approximately $0.10 per share at mid-January 2026 exchange rates. This range includes a one-time charge of approximately $9.0 billion, or approximately $3.65 per share, as well as approximately $0.30 per share of related financing and operational costs, related to the acquisition of Cidara. In 2025, non-GAAP EPS of $8.98 was negatively impacted by one-time charges of $0.20 per share related to certain business development transactions. Consistent with past practice, the financial outlook does not assume additional significant potential business development transactions. Non-GAAP EPS excludes acquisition- and divestiture-related costs, costs related to restructuring programs, as well as income and losses from investments in equity securities. Earnings Conference Call Investors, journalists and the general public may access a live audio webcast of the call on Tuesday, Feb. 3, at 9 a.m. ET via this weblink. A replay of the webcast, along with the sales and earnings news release, supplemental financial disclosures and slides highlighting the results, will be available on the Company’s website. All participants may join the call by dialing (800) 369-3351 (U.S. and Canada Toll-Free) or (517) 308-9448 and using the access code 9818590. About Our Company At Merck & Co., Inc., Rahway, N.J., USA, known as MSD outside of the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. Forward-Looking Statement of Merck & Co., Inc., Rahway, N.J., USA This news release of Merck & Co., Inc., Rahway, N.J., USA (the “Company”) includes “forward-looking statements” within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. These statements are based upon the current beliefs and expectations of the Company’s management and are subject to significant risks and uncertainties. There can be no guarantees with respect to pipeline candidates that the candidates will receive the necessary regulatory approvals or that they will prove to be commercially successful. If underlying assumptions prove inaccurate or risks or uncertainties materialize, actual results may differ materially from those set forth in the forward-looking statements. Risks and uncertainties include but are not limited to, general industry conditions and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; the Company’s ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign risk; dependence on the effectiveness of the Company’s patents and other protections for innovative products; and the exposure to litigation, including patent litigation, and/or regulatory actions. The Company undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events or otherwise. Additional factors that could cause results to differ materially from those described in the forward-looking statements can be found in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024 and the Company’s other filings with the Securities and Exchange Commission (SEC) available at the SEC’s Internet site (www.sec.gov). Appendix Generic product names are provided below. Pharmaceutical BRIDION (sugammadex) CAPVAXIVE (Pneumococcal 21-valent Conjugate Vaccine) ENFLONSIA (clesrovimab-cfor) GARDASIL (Human Papillomavirus Quadrivalent [Types 6, 11, 16 and 18] Vaccine, Recombinant) GARDASIL 9 (Human Papillomavirus 9-valent Vaccine, Recombinant) JANUMET (sitagliptin and metformin HCl) JANUVIA (sitagliptin) KEYTRUDA (pembrolizumab) KEYTRUDA QLEX (pembrolizumab and berahyaluronidase alfa-pmph) LAGEVRIO (molnupiravir) Lenvima (lenvatinib) Lynparza (olaparib) M-M-R II (Measles, Mumps and Rubella Virus Vaccine Live) OHTUVAYRE (ensifentrine) PREVYMIS (letermovir) PROQUAD (Measles, Mumps, Rubella and Varicella Virus Vaccine Live) Reblozyl (luspatercept-aamt) ROTATEQ (Rotavirus Vaccine, Live, Oral, Pentavalent) Simponi (golimumab) VARIVAX (Varicella Virus Vaccine Live) VAXNEUVANCE (Pneumococcal 15-valent Conjugate Vaccine) WELIREG (belzutifan) WINREVAIR (sotatercept-csrk) Animal Health BRAVECTO (fluralaner) ____________________ 1 Net income attributable to the Company. 2 The Company is providing certain 2025 and 2024 non-GAAP information that excludes certain items because of the nature of these items and the impact they have on the analysis of underlying business performance and trends. Management believes that providing this information enhances investors’ understanding of the Company’s results because management uses non-GAAP results to assess performance. Management uses non-GAAP measures internally for planning and forecasting purposes and to measure the performance of the Company along with other metrics. In addition, annual employee compensation, including senior management’s compensation, is derived in part using a non-GAAP pretax income metric. This information should be considered in addition to, but not as a substitute for or superior to, information prepared in accordance with GAAP. For a description of the non-GAAP adjustments, see Table 2a attached to this release. 3 Reflects expenses related to business combinations, including the amortization of intangible assets, intangible asset impairment charges, and expense or income related to changes in the estimated fair value measurement of liabilities for contingent consideration. Also includes integration, transaction and certain other costs associated with acquisitions and divestitures, as well as amortization of intangible assets related to collaborations, licensing arrangements and asset acquisitions, and recognition of fair value step-up to inventories for asset acquisitions. 4 Includes the estimated tax impacts on the reconciling items based on applying the statutory rate of the originating territory of the non-GAAP adjustments for all periods presented. Amount in the full year of 2025 also includes a $60 million net benefit, which reflects a net benefit related to favorable audit reserve adjustments. Amounts in the fourth quarter and full year of 2024 also include a $260 million benefit and a $519 million benefit, respectively, due to reductions in reserves for unrecognized income tax benefits resulting from the expiration of the statute of limitations for assessments related to certain federal tax return years. The benefit recognized in the fourth quarter of 2024 relates to the 2020 federal tax return year and the benefit for the full year of 2024 relates to both the 2020 and 2019 federal tax return years. 4Q25 4Q24 $ 16,400 $ 15,624 5% $ 65,011 $ 64,168 1% 5,551 3,828 45% 16,382 15,193 8% 2,898 2,864 1% 10,733 10,816 -1% 3,886 4,585 -15% 15,789 17,938 -12% 213 51 889 309 432 126 151 (24 ) 3,420 4,170 -18% 21,067 19,936 6% 458 425 2,804 2,803 2,962 3,745 -21% 18,263 17,133 7% (1 ) 2 9 16 $ 2,963 $ 3,743 -21% $ 18,254 $ 17,117 7% $ 1.19 $ 1.48 -20% $ 7.28 $ 6.74 8% 2,488 2,537 2,507 2,541 13.4 % 10.2 % 13.3 % 14.1 % $ 5,551 1,054 1,173 2,227 $ 3,324 2,898 48 2 50 2,848 3,886 5 (111 ) (106 ) 3,992 213 213 213 – 432 206 206 226 3,420 (1,107 ) (1,277 ) (206 ) (2,590 ) 6,010 458 (187 ) (3) (234 ) (3) (44 ) (3) (465 ) 923 2,962 (920 ) (1,043 ) (162 ) (2,125 ) 5,087 2,963 (920 ) (1,043 ) (162 ) (2,125 ) 5,088 $ 1.19 (0.37 ) (0.42 ) (0.06 ) (0.85 ) $ 2.04 13.4 % 15.4 % $ 16,382 2,871 1,484 4,355 $ 12,027 10,733 120 3 123 10,610 15,789 19 175 194 15,595 889 889 889 – 151 (3 ) (306 ) (309 ) 460 21,067 (3,007 ) (2,551 ) 306 (5,252 ) 26,319 2,804 (525 ) (3) (473 ) (3) 65 (3) (60 ) (4) (993 ) 3,797 18,263 (2,482 ) (2,078 ) 241 60 (4,259 ) 22,522 18,254 (2,482 ) (2,078 ) 241 60 (4,259 ) 22,513 $ 7.28 (0.99 ) (0.83 ) 0.10 0.02 (1.70 ) $ 8.98 13.3 % 14.4 % 2025 2024 4Q Full Year $15,529 $15,806 $17,276 $16,400 $65,011 $15,775 $16,112 $16,657 $15,624 $64,168 5 4 1 2 13,638 14,050 15,611 14,843 58,142 14,006 14,408 14,943 14,042 57,400 6 4 1 1 7,205 7,956 8,142 8,337 31,641 6,947 7,270 7,429 7,836 29,482 6 5 7 7 5 35 40 - - - - 312 370 379 389 1,450 292 317 337 365 1,311 7 4 11 10 258 265 258 272 1,053 255 249 251 255 1,010 7 6 4 4 137 162 196 220 716 85 126 139 160 509 37 37 41 41 119 107 136 164 525 71 90 100 110 371 48 48 41 41 1,327 1,126 1,749 1,031 5,233 2,249 2,478 2,306 1,550 8,583 -34 -35 -39 -39 539 609 684 619 2,451 570 617 703 594 2,485 4 3 -1 -2 230 229 226 140 825 219 189 239 161 808 -13 -16 2 1 107 129 244 279 759 47 50 97 228 121 204 119 673 216 163 193 139 711 -14 -15 -5 -5 41 38 45 42 166 61 59 68 74 263 -43 -44 -37 -37 441 461 439 499 1,841 440 455 420 449 1,764 11 11 4 4 208 228 266 275 978 174 188 208 215 785 28 26 25 23 70 74 81 87 312 56 62 64 70 252 24 23 24 24 83 96 43 25 247 73 92 96 79 340 -68 -68 -27 -27 280 336 360 467 1,443 70 149 200 419 133 133 106 123 112 129 470 98 106 102 109 415 18 18 13 13 68 80 82 83 312 70 72 72 73 287 14 9 9 6 178 178 - - - - 102 83 138 57 380 350 110 383 121 964 -53 -53 -61 -61 90 86 82 67 325 111 89 102 92 394 -27 -28 -18 -18 67 83 77 79 306 56 60 65 69 249 15 9 23 20 45 41 43 42 171 42 39 42 40 163 6 4 5 4 50 40 47 49 186 46 53 78 45 222 8 9 -16 -16 184 172 189 543 -100 -100 39 35 41 114 -100 -100 549 372 382 302 1,604 419 405 278 232 1,334 30 30 20 21 247 251 243 199 940 251 224 204 255 935 -22 -22 1 2 729 584 948 658 2,917 632 618 638 699 2,590 -6 -5 13 13 1,588 1,646 1,615 1,505 6,354 1,511 1,482 1,487 1,397 5,877 8 6 8 9 924 961 1,023 987 3,896 850 837 886 889 3,462 11 9 13 14 664 685 592 518 2,458 661 645 601 508 2,415 2 0 2 2 303 110 50 52 515 258 222 227 185 891 -71 -15 -42 -6

January 8, 2026 4:57 pm EST Rahway, N.J., Jan. 8, 2026 – At Merck, we share the same fundamental belief with health care providers and parents alike: every child deserves to grow up safe, healthy and able to thrive. Nothing is more important to us than the safety of our medicines and vaccines and the wellbeing of the people who rely on them. For many families today, diseases such as measles, polio and hepatitis B may feel like distant history. That progress exists because childhood vaccination has been remarkably successful. Decades of science-based immunization policy, supported by continuous safety monitoring and real-life evidence across millions of children, have helped protect communities. The U.S. child and adolescent immunization schedule has long reflected this rigorous approach. Vaccines are studied extensively in clinical trials using specific dosing regimens, and vaccinations are timed based on multiple scientific considerations, including when maternal antibodies wane, when children are most likely to be exposed to or susceptible to certain diseases, how immune systems respond at different ages and how healthcare providers can most effectively deliver protection. As the Department of Health and Human Services (HHS) makes changes to the immunization schedule, it is critical that changes are informed by comprehensive data and guided by experts in vaccinology, pediatrics, infectious diseases and epidemiology. International comparisons should also be evaluated in the proper context, recognizing differences in disease burden, healthcare infrastructure and population needs. Shared clinical decision-making plays an important role in healthcare, helping clinicians and families consider individual circumstances and risks. However, clear, evidence-based recommendations remain essential to support informed decisions and ensure that children and adolescents receive reliable protection against preventable diseases. As recent outbreaks in the U.S. have shown, sustained confidence in vaccination programs is critical to protecting individuals and communities. When vaccination rates decline, the consequences can be serious. Merck stands firmly behind an immunization framework grounded in rigorous science, strong regulatory processes and ongoing safety monitoring. We remain committed to working with public health partners to support policies that help protect children and adolescents, strengthen communities and preserve the progress achieved through immunization. Indication for M-M-R®II M-M-R®II is a vaccine indicated for active immunization for the prevention of measles, mumps, and rubella in individuals 12 months of age or older. The first dose of M-M-R®II is administered at 12 to 15 months of age and the second dose of M-M-R®II is administered at 4 to 6 years of age. Select Safety Information for M-M-R®II M-M-R®II is contraindicated in certain individuals, including those with: a history of hypersensitivity to any component of the vaccine, including gelatin; a history of anaphylactic reaction to neomycin; individuals who are immunodeficient or immunosuppressed due to disease or medical therapy; an active febrile illness; active untreated tuberculosis; or those who are pregnant or are planning to become pregnant within the next month. Due caution should be employed in administration of M-M-R®II to persons with: a history of febrile seizure or family history of febrile seizures; immediate-type hypersensitivity reactions to eggs; thrombocytopenia. Vaccination should be deferred in individuals with a family history of congenital or hereditary immunodeficiency until the individual’s immune status has been evaluated and the individual has been found to be immunocompetent. Immune globulins (IG) and other blood products should not be given concurrently with M-M-R®II. The ACIP has specific recommendations for intervals between administration of antibody-containing products and live virus vaccines. The following adverse reactions have been identified during both the subcutaneous and intramuscular use of M-M-R®II or its components in clinical trials or reported during post-approval use: fever, rash, and injection-site reactions. The following adverse reactions have been identified during the subcutaneous use of M-M-R®II or its components in clinical trials or reported during post-approval use: headache, dizziness, febrile convulsions, anaphylaxis and anaphylactoid reactions, arthritis, thrombocytopenia, encephalitis and encephalopathy. Dosage and Administration for M-M-R®II FOR INTRAMUSCULAR OR SUBCUTANEOUS USE ONLY. M-M-R®II vaccine can be administered concurrently with other live viral vaccines. If not given concurrently, M-M-R®II vaccine should be given one month before or one month after administration of other live viral vaccines to avoid potential for immune interference. Before administering M-M-R®II, please read the accompanying Prescribing Information. The Patient Information also is available. Indication for ProQuad® ProQuad is a vaccine indicated for active immunization for the prevention of measles, mumps, rubella, and varicella in children 12 months through 12 years of age. VARIVAX is a vaccine indicated for active immunization for the prevention of varicella in individuals 12 months of age or older. M-M-R®II is indicated for active immunization for the prevention of measles, mumps, and rubella in individuals 12 months of age or older. Select Safety Information for ProQuad Hypersensitivity: ProQuad, M-M-R®II (Measles, Mumps, and Rubella Virus Vaccine Live), and VARIVAX® (Varicella Virus Vaccine Live)are contraindicated in patients with a history of anaphylactic reaction or hypersensitivity to any component of the vaccine (including gelatin or neomycin) or to a prior dose of measles, mumps, rubella, or varicella-containing vaccine. Use caution when administering ProQuad and M‑M‑R®II to individuals with anaphylaxis or immediate hypersensitivity to eggs. ProQuad, M-M-R®II, and VARIVAXare contraindicated in certain individuals, including those with: immunodeficiency or who are immunosuppressed; an active febrile illness; untreated tuberculosis. Pregnancy: ProQuad, M-M-R®II, and VARIVAX are contraindicated for use in pregnant women. Do not administer ProQuad or VARIVAX to individuals who are planning to become pregnant in the next 3 months. Do not administer M-M-R®II to individuals who are planning to become pregnant in the next month. Febrile Seizures: Administration of ProQuad (dose 1) to children 12 to 23 months old who have not been previously vaccinated against measles, mumps, rubella, or varicella, nor had a history of the wild-type infections, is associated with higher rates of fever and febrile seizures at 5 to 12 days after vaccination when compared to children vaccinated with a first dose of both M-M-R®II and VARIVAX administered concomitantly. Febrile Seizures: Use caution when administering ProQuad and M-M-R®II to individuals with a history of febrile seizures. Family History of Immunodeficiency: Vaccination with ProQuad, M-M-R®II, and VARIVAX should be deferred in individuals with a family history of congenital or hereditary immunodeficiency until the individual’s immune status has been evaluated and the individual has been found to be immunocompetent. Thrombocytopenia: Transient thrombocytopenia has been reported within 4-6 weeks following vaccination with measles, mumps, and rubella vaccine. Carefully evaluate the potential risk and benefit of vaccination in children with thrombocytopenia or in those who experienced thrombocytopenia after vaccination with a previous dose of a measles, mumps, and rubella-containing vaccine. Varicella Transmission and Precautions: Advise vaccinees administered ProQuad or VARIVAX to avoid: close contact with high-risk individuals susceptible to varicella for up to 6 weeks following vaccination since transmission of varicella vaccine virus to susceptible contacts has been reported. Varicella vaccine virus transmission may occur between vaccine recipients and contacts susceptible to varicella including healthy individuals. Immune Globulins and Other Blood Products: Immune Globulins and other blood products should not be given concomitantly with ProQuad, M-M-R®II, or VARIVAX. Use of Salicylates: Avoid use of salicylates in children and adolescents administered ProQuad or VARIVAX for 6 weeks following vaccination due to the association of Reye Syndrome with salicylate therapy and wild-type varicella infection. Adverse Events: The following adverse events have been reported for both subcutaneous and intramuscular injections of ProQuad, M-M-R®II, and VARIVAX: fever, injection-site reactions (pain/tenderness/soreness, erythema, and swelling); and rash on the body or at the injection site. Additionally, irritability has been reported for the subcutaneous injections of ProQuad, M-M-R®II, and VARIVAX. ProQuad Systemic Vaccine-Related Adverse Events: Systemic vaccine-related adverse events that were reported at a significantly greater rate in recipients of subcutaneous ProQuad than in recipients of the component vaccines administered concomitantly were fever and measles-like rash. VARIVAX Dose-related Adverse Events: In a clinical trial involving children who received 2 doses of VARIVAX 3 months apart, the incidence of injection-site clinical complaints observed in the first 4 days following vaccination was slightly higher post-dose 2 (overall incidence 25.4%) than post-dose 1 (overall incidence 21.7%), whereas the incidence of systemic clinical complaints in the 42-day follow-up period was lower post-dose 2 (66.3%) than post-dose 1 (85.8%). Concomitant Vaccines With ProQuad: ProQuad may be administered concomitantly with diphtheria and tetanus toxoids and acellular pertussis vaccine adsorbed (DTaP), Haemophilus influenzae type b conjugate (meningococcal protein conjugate) and hepatitis B (recombinant) vaccine. It may also be administered concomitantly with pneumococcal 7-valent conjugate vaccine and/or hepatitis A vaccine (inactivated) at separate injection sites. Concomitant Vaccines With VARIVAX: VARIVAX can be administered with other live viral vaccines. If not given concurrently, at least 1 month should elapse between a dose of a live attenuated measles virus-containing vaccine and a dose of VARIVAX. In children, at least 3 months should elapse between administration of 2 doses of a live attenuated varicella virus-containing vaccine. Tuberculin Testing: If a tuberculin test is to be done with M-M-R®II and ProQuad, it should be administered either any time before, simultaneously with, or at least 4 to 6 weeks after vaccination. With VARIVAX, tuberculin testing may be performed before the vaccine is administered or at least 4 weeks following vaccination. Additional M-M-R®II Precautions: Additional adverse reactions, which have been reported without regard to causality, include febrile convulsions, arthritis, thrombocytopenia, anaphylaxis, anaphylactoid reactions, arthritis, encephalitis and encephalopathy in their diverse clinical presentations. Additional VARIVAX Precautions: It is not known if varicella vaccine virus is excreted in human milk. A boost in antibody levels has been observed in vaccinees following exposure to wild-type varicella, which could account for the apparent long-term persistence of antibody levels in studies. The duration of protection from varicella infection after vaccination is unknown. ProQuad/VARIVAX and Herpes Zoster: The long-term effect of VARIVAX on the incidence of herpes zoster, particularly in those vaccinees exposed to wild-type varicella, is unknown at present. Efficacy: Vaccination with ProQuad, VARIVAX, or M-M-R®II may not result in protection in 100% of vaccinees. Dosage and Administration for ProQuad ProQuad: Each dose of ProQuad is approximately 0.5 mL and is administered intramuscularly or subcutaneously. At least 1 month should elapse between a dose of a measles-containing vaccine such as M-M-R®II and a dose of ProQuad. At least 3 months should elapse between a dose of varicella-containing vaccine and ProQuad. VARIVAX: Each dose is approximately 0.5 mL and is administered intramuscularly or subcutaneously. The first dose is administered at 12 to 15 months of age. The second dose is administered at 4 to 6 years of age. There should be a minimum interval of 3 months between doses. 12 months to 12 years of age: If a second dose is administered, there should be a minimum interval of 3 months between doses. Adolescents (≥13 years of age) and Adults: 2 doses, to be administered with aminimum interval of 4 weeks between doses. The first dose is administered at 12 to 15 months of age. The second dose is administered at 4 to 6 years of age. There should be a minimum interval of 3 months between doses. 12 months to 12 years of age: If a second dose is administered, there should be a minimum interval of 3 months between doses. Adolescents (≥13 years of age) and Adults: 2 doses, to be administered with aminimum interval of 4 weeks between doses. M-M-R®II: The dose for any age is approximately 0.5 mL administered intramuscularly or subcutaneously. The recommended age for primary vaccination is 12 to 15 months and the second dose should be given at 4 to 6 years of age. The recommended age for primary vaccination is 12 to 15 months and the second dose should be given at 4 to 6 years of age. Before administering VARIVAX (Varicella Virus Vaccine Live), M-M-R®II (Measles, Mumps, and Rubella Virus Vaccine Live), or ProQuad (Measles, Mumps, Rubella and Varicella Virus Vaccine Live), please read the accompanying Prescribing Information. The Patient Information also is available for VARIVAX , M-M-R®II , and ProQuad. Indication for RECOMBIVAX HB® RECOMBIVAX HB is indicated for prevention of infection caused by all known subtypes of hepatitis B virus. RECOMBIVAX HB is approved for use in individuals of all ages. RECOMBIVAX HB Dialysis Formulation is approved for use in adult predialysis and dialysis patients 18 years of age and older. Select Safety Imformation for RECOMBIVAX HB Do not administer RECOMBIVAX HB to individuals with a history of severe allergic or hypersensitivity reactions (eg, anaphylaxis) after a previous dose of any hepatitis B-containing vaccine or to any component of RECOMBIVAX HB, including yeast. The vial stopper and the syringe plunger stopper and tip cap contain dry natural latex rubber, which may cause allergic reactions in latex-sensitive individuals. Apnea following intramuscular vaccination has been observed in some infants born prematurely. Decisions about when to administer an intramuscular vaccine, including RECOMBIVAX HB, to infants born prematurely should be based on consideration of the individual infant’s medical status and the potential benefits and possible risks of vaccination. For RECOMBIVAX HB, this assessment should include consideration of the mother’s hepatitis B antigen status and high probability of maternal transmission of hepatitis B virus to infants born to mothers who are HBsAg positive if vaccination is delayed. Hepatitis B vaccination should be delayed until 1 month of age or hospital discharge in infants weighing <2000 g if the mother is documented to be HBsAg negative at the time of the infant’s birth. Infants weighing <2000 g born to HBsAg positive or HBsAg unknown mothers should receive vaccine and hepatitis B immune globulin (HBIG) in accordance with ACIP recommendations if HBsAg status cannot be determined. Hepatitis B virus has a long incubation period. RECOMBIVAX HB may not prevent hepatitis B infection in individuals who have an unrecognized hepatitis B infection at the time of vaccination. Vaccination with RECOMBIVAX HB may not protect all individuals. In healthy infants and children (up to 10 years of age), injection site reactions and systemic adverse reactions were reported following 0.2% and 10.4% of the injections, respectively. The most frequently reported systemic adverse reactions (>1% injections), in decreasing order of frequency, were irritability, fever, diarrhea, fatigue/weakness, diminished appetite, and rhinitis. In a study that compared the 3-dose regimen (5 mcg) with the 2-dose regimen (10 mcg) of RECOMBIVAX HB in adolescents, the overall frequency of adverse reactions was generally similar. In a group of studies involving healthy adults, injection site reactions and systemic adverse reactions were reported following 17% and 15% of the injections, respectively. The following adverse reactions were reported (≥1% of injections) injection site reactions, fatigue/weakness, headache, fever, malaise, nausea, diarrhea, pharyngitis, and upper respiratory infection. Additional adverse reactions have been reported with the use of the marketed vaccine. Because these reactions are reported voluntarily from a population of uncertain size, it is not possible to reliably estimate their frequency or establish a causal relationship to a vaccine exposure. Use in Special Populations Pregnancy There are no adequate and well-controlled studies designed to evaluate RECOMBIVAX HB in pregnant women. Available post-approval data do not suggest an increased risk of miscarriage or major birth defects in women who received RECOMBIVAX HB during pregnancy. Nursing Mothers Data are not available to assess the effects of RECOMBIVAX HB on the breastfed infant or on milk productions/excretion. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for RECOMBIVAX HB and any potential adverse effects on the breastfed child from RECOMBIVAX HB or from the underlying maternal condition. Pediatric Use The safety and effectiveness of RECOMBIVAX HB Dialysis Formulation in children have not been established. Geriatric Use Clinical studies of RECOMBIVAX HB did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. However, in later studies it has been shown that a diminished antibody response can be expected in persons older than 60 years of age. In addition, the responses to these vaccines may be lower if the vaccine is administered as a buttock injection. Predialysis and Dialysis Patients Predialysis and dialysis adult patients respond less well to hepatitis B vaccines than do healthy individuals; however, vaccination of adult patients early in the course of their renal disease produces higher seroconversion rates than vaccination after dialysis has been initiated. Known or Presumed Exposure to HBsAg Refer to recommendations of the Advisory Committee on Immunization Practices (ACIP) and to the package insert for hepatitis B immune globulin (HBIG) for management of persons with known or presumed exposure to the hepatitis B virus (eg, neonates born of infected mothers or persons who experienced percutaneous or permucosal exposure to the virus). When recommended, administer RECOMBIVAX HB and HBIG intramuscularly at separate sites (eg, opposite anterolateral thighs for exposed neonates) as soon as possible after exposure. Dosage and Administration for RECOMBIVAX HB The vaccination regimen for RECOMBIVAX HB for persons from birth through 19 years of age consists of a series of 3 doses (0.5 mL each) given on a 0-, 1-, and 6-month schedule. The vaccination regimen for RECOMBIVAX HB for adolescents 11 through 15 years of age consists of a series of 3 doses (0.5 mL each) given on a 0-, 1-, and 6-month schedule, or a series of 2 doses (1.0 mL each) on a 0- and 4- to 6-month schedule. The vaccination regimen for RECOMBIVAX HB for persons 20 years of age and older consists of a series of 3 doses (1.0 mL each) given on a 0-, 1-, and 6-month schedule. The deltoid muscle is the preferred site for intramuscular injection for adults, adolescents, and children 1 year of age and older whose deltoid is large enough for intramuscular injection. The anterolateral aspect of the thigh is the preferred site for intramuscular injection for infants younger than 1 year of age. RECOMBIVAX HB should not be administered in the gluteal region, as injections given in the buttocks have resulted in lower seroconversion rates than expected. Consider subcutaneous administration only in persons who are at risk of hemorrhage following intramuscular injections. Predialysis and Dialysis Adult Patients: The vaccination regimen for RECOMBIVAX HB Dialysis Formulation for adults on predialysis and dialysis consists of a series of 3 doses (1.0 mL each) given on a 0-, 1-, and 6-month schedule. Consider a booster dose or revaccination with RECOMBIVAX HB Dialysis Formulation (blue color code) in predialysis/dialysis patients if the anti-HBs level is less than 10 mIU/mL at 1 to 2 months after the third dose. The duration of the protective effect on RECOMBIVAX HB in healthy vaccinees is unknown at present and the need for booster doses is not yet defined. RECOMBIVAX HB should be administered as soon as possible after being removed from refrigeration. Before administering RECOMBIVAX HB, please read the accompanying Prescribing Information. Indication for VAXELIS® VAXELIS is a vaccine indicated for active immunization to prevent diphtheria, tetanus, pertussis, poliomyelitis, hepatitis B, and invasive disease due to Haemophilus influenzaetype b. VAXELIS is approved for use as a 3-dose series in children 6 weeks through 4 years of age (prior to the 5th birthday). Select Safety Information for VAXELIS VAXELIS is contraindicated in children with a history of severe allergic reaction (eg, anaphylaxis) to a previous dose of VAXELIS, any ingredient of VAXELIS, or any other diphtheria toxoid, tetanus toxoid, pertussis-containing vaccine, inactivated poliovirus vaccine, hepatitis B vaccine, or H. influenzaetype b vaccine. Do not administer VAXELIS to anyone with a history of encephalopathy (e.g., coma, decreased level of consciousness, prolonged seizures), within 7 days of a pertussis-containing vaccine that is not attributable to another identifiable cause. Do not administer VAXELIS to anyone with a history of progressive neurologic disorder until a treatment regimen has been established and the condition has stabilized. Vaccination with VAXELIS may not protect all individuals. Carefully consider benefits and risks before administering VAXELIS to persons with a history of: fever of ≥40.5°C (≥105°F), hypotonic-hyporesponsive episode (HHE) or persistent, inconsolable crying lasting ≥3 hours within 48 hours after a previous pertussis-containing vaccine. seizures within 3 days after a previous pertussis-containing vaccine. If Guillain-Barré syndrome occurred within 6 weeks of receipt of a prior vaccine containing tetanus toxoid, the risk for Guillain-Barré syndrome may be increased following VAXELIS. Apnea following intramuscular vaccination has been observed in some infants born prematurely. The decision about when to administer an intramuscular vaccine, including VAXELIS, to an infant born prematurely should be based on considerations of the individual infant’s medical status and the potential benefits and possible risks of vaccination. Urine antigen detection may not have definitive diagnostic value in suspected H. influenzatype b disease following vaccination with VAXELIS. The solicited adverse reactions following any dose were irritability (≥55%), crying (≥45%), injection site pain (≥44%), somnolence (≥40%), injection site erythema (≥25%), decreased appetite (≥23%), fever ≥38.0°C (≥19%), injection site swelling (≥18%), and vomiting (≥9%). Dosage and Administration for VAXELIS The 3-dose immunization series consists of a 0.5 mL intramuscular injection, administered at 2, 4, and 6 months of age. A 3-dose series of VAXELIS does not constitute a primary immunization series against pertussis; an additional dose of pertussis-containing vaccine is needed to complete the primary series. Before administering VAXELIS, please read the accompanying Prescribing Information. The Patient Information also is available. About Merck At Merck, known as MSD outside of the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit www.merck.com and connect with us on X (formerly Twitter), Facebook, Instagram, YouTube and LinkedIn. Forward-Looking Statement of Merck & Co., Inc., Rahway, N.J., USA This news release of Merck & Co., Inc., Rahway, N.J., USA (the “company”) includes “forward-looking statements” within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. These statements are based upon the current beliefs and expectations of the company’s management and are subject to significant risks and uncertainties. If underlying assumptions prove inaccurate or risks or uncertainties materialize, actual results may differ materially from those set forth in the forward-looking statements. Risks and uncertainties include but are not limited to, general industry conditions and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; the company’s ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign risk; dependence on the effectiveness of the company’s patents and other protections for innovative products; and the exposure to litigation, including patent litigation, and/or regulatory actions. The company undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events or otherwise. Additional factors that could cause results to differ materially from those described in the forward-looking statements can be found in the company’s Annual Report on Form 10-K for the year ended December 31, 2024 and the company’s other filings with the Securities and Exchange Commission (SEC) available at the SEC’s Internet site (www.sec.gov). 1 VAXELIS™ is the result of the U.S.-based business joint-partnership (MCM) created in 1991 between Merck & Co., Inc., Connaught Laboratories and Pasteur Mérieux Serums & Vaccins, the latter two now known as Sanofi Pasteur, the vaccines unit of Sanofi. Media Contacts: Melissa Moody (732) 594-1530 melissa.moody@merck.com Alayna Shamy (732) 403-0397 alayna.shamy@merck.com Investor Contacts: Peter Dannenbaum (732) 594-1579 peter.dannenbaum@merck.com Damini Chokshi (732) 594-1577 damini.chokshi@merck.com