Merck gains FDA approval for its first adult pneumococcal vaccine

Merck has achieved a significant milestone by securing FDA approval for Capvaxive (formerly V116), the first pneumococcal vaccine specifically designed for older adults. The vaccine's approval marks a new chapter in the fight against pneumococcal disease, particularly for individuals aged 50 and above.

Capvaxive, targeting 21 serotypes, has demonstrated its ability to cover 84% of the pneumococcal disease cases in people over 50, based on epidemiological data from the CDC. In comparison, Pfizer's Prevnar 20, which is currently the leading pneumococcal vaccine, covers 52% of cases in the same age group. However, there have been no direct efficacy studies comparing Capvaxive and Prevnar 20.

The approval of Capvaxive is backed by four phase 3 clinical trials. One of these trials compared Capvaxive to Prevnar 20, focusing on immune responses. The results highlighted Capvaxive's non-inferiority in the 10 serotypes common to both vaccines and its superiority in 10 of its 11 unique serotypes. According to Heather Platt, M.D., Merck’s pneumococcal vaccine lead, eight serotypes in Capvaxive are not found in any other currently licensed vaccine and are responsible for 30% of invasive pneumococcal disease in adults aged 65 and older.

Despite the FDA's accelerated approval, further verification of Capvaxive’s clinical benefits in a confirmatory study is required. On June 27, the CDC’s Advisory Committee on Immunization Practices (ACIP) will convene to discuss recommendations for Capvaxive’s use.

Merck’s focus on developing a pneumococcal vaccine for adults positions it ahead of other companies. California-based biotech firm Vaxcyte is developing a 24-valent shot, covering all serotypes in Prevnar 20 plus four unique strains. Vaxcyte is also working on a 31-valent pneumococcal vaccine.

The journey to create an adult-adapted pneumococcal vaccine has been extensive. The first vaccine for this infection, a polysaccharide type, was introduced in 1977. The introduction of the first conjugate vaccine, Prevnar 7 (PCV7), in 2000 significantly reduced the disease burden in both children and adults. However, later conjugate vaccines with additional serotypes proved more effective in children than adults, prompting researchers to investigate the cause.

Platt noted that over time, surveillance data revealed that the serotypes causing disease in children differ from those affecting adults. Each year in the United States, over 150,000 adults are hospitalized with pneumococcal disease, which can lead to severe complications like bacteremia and pneumococcal meningitis, with a case death rate of 14%.

While protecting children has historically been the primary focus of pneumococcal vaccines, recent years have seen a shift towards adult vaccination. Platt emphasized the growing recognition of the value of adult vaccination within CDC work groups and ACIP discussions.

Merck plans to target a broad demographic with Capvaxive. Currently, around 34% of adults aged 65 and older in the U.S. have never received a pneumococcal shot. Even those who have been vaccinated can benefit from Capvaxive’s protection against new serotypes. Additionally, a significant number of adults with chronic medical conditions, such as lung, liver, or heart disease, remain unvaccinated against pneumococcal disease despite being at higher risk.

Platt highlighted the importance of understanding how to effectively provide vaccination opportunities, whether through better access or increased awareness of the vaccine’s benefits.

Merck stands to expand its share of the pneumococcal vaccine market with Capvaxive. In 2023, the company achieved $665 million in sales from its 15-valent pneumococcal shot, Vaxneuvance (formerly V114), approved in 2021. While Pfizer’s Prevnar franchise remains the market leader with $6.4 billion in sales last year, Merck’s vaccine has contributed to a slowdown in Prevnar’s sales growth.

Capvaxive is seen as a complement to pediatric vaccines, with the goal of enhancing public health. The upcoming ACIP vote is anticipated with the hope of further improving vaccination rates among adults.