Vaxcyte Surges 57% on Positive Phase 3 Data for VAX-31 Pneumococcal Vaccine

Vaxcyte shares jumped 57% in pre-market trading Monday after the company reported positive results from OPUS-1, a pivotal phase 3 trial of its 31-valent pneumococcal vaccine candidate VAX-31, positioning it against Pfizer's Prevnar 20 and Merck's Capvaxive. VAX-31 met all prespecified primary endpoints across age groups studied. Among adults 50 and older, it demonstrated noninferiority against Prevnar 20 across all 20 shared serotypes and against Capvaxive on 17 of 19 shared serotypes, with noninferiority defined as a lower bound of the 95% confidence interval above 0.667. For serotypes 3 and 12F against Capvaxive, VAX-31 still cleared a lower historical threshold of 0.5. The vaccine also showed superior immune responses on three strains unique to it and one cross-reactive serotype. The trial enrolled 4,047 participants at roughly 30 U.S. sites. Vaxcyte plans to submit a Biologics License Application to the FDA in the first half of 2028.