Vaxcyte said its next-generation pneumococcal vaccine, VAX-31, met key endpoints in a Phase 3 trial in adults age 50 and older, setting up a direct push into the crowded market dominated by Pfizer and Merck. The trial randomized just over 3,500 participants across VAX-31, Prevnar, and Capvaxive arms and evaluated antibody responses across targeted serotypes.