Vaxcyte said its pneumococcal conjugate vaccine VAX-31 met primary endpoints in a Phase 3 trial in adults 50 and older, driving a sharp jump in shares. The company positions the 31-valent product against established multi-serotype incumbents. In the trial, VAX-31 was compared with Pfizer’s Prevnar and Merck’s Capvaxive, with antibody responses measured across included pneumococcal strains. Vaxcyte’s results also support its strategy to expand beyond earlier, narrower coverage. For investors and planners, the readout reduces a key development risk and raises the probability of competitive label expansion as the vaccine market moves toward broader serotype coverage.