20-valent Pneumococcal Conjugate Vaccine(Pfizer)

Pfizer's paediatric vaccine reaches Phase 3 of trials. Credit: Pfizer Encouraging Phase 2 results show a robust immune response against serotype 3, prompting pivotal Phase 3 trials to protect up to 90% of paediatric patients Pfizer has announced the advancement of its pivotal paediatric pneumococcal vaccine programme following encouraging data from its Phase 2 clinical trial. The company has initiated its Phase 3 clinical trial for an investigational 25-valent pneumococcal conjugate vaccine candidate, designated PF-07872412 or 25vPnC, in infants. Alongside this milestone, Pfizer has unveiled plans to progress its adult vaccine strategy by moving straight to a fifth-generation 35-valent candidate. Strong immunogenicity shown in phase 2 results The decision to progress into a Phase 3 programme follows positive data from a Phase 2 study evaluating the safety, tolerability and immunogenicity of a four-dose series of the 25vPnC candidate in healthy infants. In this randomised trial, which began initial enrolment in July 2024, participants received either the 25vPnC candidate or the existing licensed standard-of-care vaccine, PREVNAR 20, at two, four, six and 12-15 months of age. Preliminary findings from the study were delivered during an oral presentation at the 14th meeting of the International Society of Pneumonia & Pneumococcal Diseases (ISPPD) in Copenhagen, Denmark. The results showed robust immune responses across all 25 included serotypes. Crucially, the investigational vaccine elicited an enhanced response against serotype 3, which continues to be a major cause of invasive pneumococcal disease and complicated pneumonia in young children. Data revealed that one month after the third dose, geometric mean titers for serotype 3 were 8.8-fold higher in infants given 25vPnC than in those who received PREVNAR 20, with scores of 4.22 versus 0.48 respectively. One month after the fourth dose, the gap widened further, with 25vPnC producing a serotype 3 immunogenicity response approximately 15-fold higher than PREVNAR 20, recording titers of 13.85 compared to 0.92. Broader disease coverage and safety The 25vPnC candidate builds upon the 20 serotypes already included in PREVNAR 20 by introducing five new serotypes: 15A, 23A, 23B, 24F and 35B. This addition expands protection to cover up to 90% of disease-causing serotypes in children under five years of age, representing an additional 25% coverage of invasive pneumococcal disease cases compared to PCV20. In terms of safety, the investigational vaccine was well-tolerated with no safety concerns identified during the Phase 2 study. The safety and tolerability profile remained consistent with currently approved pneumococcal vaccines, with the most common local reactions being typical injection site symptoms such as redness, swelling or pain. Annaliesa Anderson, Ph.D., Senior Vice President and Chief Vaccines Officer, Pfizer “For more than 25 years, our vaccines have helped protect children from pneumococcal disease, yet a significant disease burden remains,” said Annaliesa Anderson, Ph.D., Senior Vice President and Chief Vaccines Officer, Pfizer. “These Phase 2 results reinforce our confidence in a next-generation vaccine designed to expand protection across serotypes while improving responses to key residual disease drivers such as serotype 3. We are advancing our Phase 3 programme with the goal of delivering broader and more durable protection for children.” Launching the paediatric phase 3 programme Based on the robust immune responses observed across the Phase 2 programme and following collaborative discussions with regulatory authorities, Pfizer officially initiated its pivotal paediatric Phase 3 programme in May 2026. The company remains confident that the candidate will meet the necessary non-inferiority thresholds required in this definitive stage of testing. The upcoming Phase 3 studies will assess the safety, tolerability and immunogenicity of 25vPnC in up to 2,400 healthy children. Participants will be allocated to receive the exact same vaccine for all four scheduled doses, comparing 25vPnC directly to the licensed 20-valent standard-of-care vaccine at two, four, six and 12 to 15 months of age. Evolution of the adult vaccine strategy Simultaneously, Pfizer has chosen a direct pathway to maintain its long-term market leadership within the adult sector. The biopharmaceutical firm has decided to bypass intermediate clinical steps and move straight to a fifth-generation adult vaccine candidate that covers 35 serotypes. This adult candidate will leverage Pfizer's proprietary next-generation technology to enhance immunogenicity for critical strains, including serotype 3, while expanding overall serotype coverage. Pending alignment with regulatory authorities, this 35-valent adult vaccine candidate is projected to enter clinical development by the end of 2026. Company portals Pfizer Executives Annaliesa Anderson, Ph.D. Senior Vice President and Chief Vaccines Officer

Pfizer on Wednesday detailed results supporting its decision to advance the investigational 25-valent pneumococcal conjugate vaccine candidate PF-07872412 into Phase III studies, including data showing stronger immune responses than the approved 20-variant shot Prevnar 20. The findings were presented at the International Society of Pneumonia & Pneumococcal Diseases (ISPPD) meeting.The results come from a Phase II study, which randomised healthy infants to receive PF-07872412 or Prevnar 20 at months 2, 4, 6 and 12–15. While Prevnar 20 is approved for the prevention of invasive disease caused by 20 Streptococcus pneumoniae strains, PF-07872412 seeks to build on this by adding protection against an additional five serotypes — 15A, 23A, 23B, 24F and 35B.In the trial, Pfizer said that PF-07872412 demonstrated "robust immunogenicity," including enhanced response against serotype 3, alongside expanded protection across the 25 serotypes. The company added that based on these immune responses, it is "confident" that the required non-inferiority thresholds will be achieved in further studies.Specifically, one month after the third dose, geometric mean titers for serotype 3 were 8.8-fold higher with PF-07872412 than with Prevnar 20 in the Phase II trial. Meanwhile, one month after dose four, geometric mean titers for serotype 3 were approximately 15-fold higher with the 25-valent vaccine than with Prevnar 20.Pfizer indicated that PF-07872412's safety profile was "consistent" with currently-approved pneumococcal vaccines, with the most common local reactions being redness, swelling or pain at the injection site."These…results reinforce our confidence in a next-generation vaccine," said Annaliesa Anderson, Pfizer's chief vaccines officer. "We are advancing our Phase III programme with the goal of delivering broader and more durable protection for children."The pivotal paediatric programme — which was initiated this month — is designed to investigate PF-07872412 versus Prevnar 20 in up to 2400 individuals. Pfizer hopes that if successful, the new vaccine will broaden protection to about 90% of disease-causing pneumococcal serotypes in US children.Prevnar 20 is currently approved in both infants and adults, with the vaccine, along with the older version Prevnar 13, generating combined sales of $6.5 billion last year. Pfizer said Wednesday that in an effort to maintain its current leadership in the adult market over the long term, it will move directly to a vaccine candidate covering 35 serotypes. The shot is expected to enter clinical development by the end of 2026.