Vaxcyte Takes Aim at Pfizer and Merck With New Pneumonia Vaccine

Vaxcyte has moved closer to challenging two of the biggest names in the pneumonia vaccine market after its experimental vaccine produced encouraging results in a late-stage clinical trial.

The California-based biotechnology company announced that VAX-31, its 31-valent pneumococcal conjugate vaccine, met the main goals of its Phase 3 OPUS-1 study. The trial involved more than 4,000 adults, including 3,572 participants aged 50 and above.

VAX-31 is being developed to protect against 31 serotypes of bacteria responsible for pneumococcal disease, including pneumonia, meningitis and bloodstream infections. That would give it broader coverage than Pfizer’s Prevnar 20, which targets 20 serotypes, and Merck’s Capvaxive, which targets 21.

In the trial, VAX-31 generated immune responses comparable to the competing vaccines across the 28 serotypes they share. It also demonstrated stronger responses against three serotypes unique to VAX-31 and serotype 20B. However, the vaccine did not meet the study’s stricter non-inferiority benchmark for two serotypes when compared with Capvaxive, although it met an older, less stringent threshold.

The results have significant commercial implications. Pfizer’s Prevnar franchise and Merck’s Capvaxive generated billions in sales, making pneumococcal vaccination an important market for both companies. Vaxcyte’s results have therefore attracted considerable investor attention, with the company’s shares surging following the announcement.

Vaxcyte is not yet ready for the market, however. Additional Phase 3 results are expected in the first half of 2027, with the company planning to submit its U.S. application for regulatory approval in the first half of 2028.

If subsequent trials and regulatory review go as planned, VAX-31 could introduce a new competitor into a vaccine market currently dominated by Pfizer and Merck.