A stronger pneumonia shot for older adults just cleared its biggest test

For older adults who dread pneumonia season, Monday brought genuine hope. Vaxcyte's experimental vaccine VAX-31 met its main goals in a late-stage trial in adults aged 50 and older, triggering immune responses at least as strong as Pfizer's Prevnar 20 and Merck's Capvaxive across the 28 bacterial strains they share — and stronger responses against three strains covered by no rival shot. The vaccine showed a consistent safety profile with no serious related side effects, and investors noticed: Vaxcyte's shares jumped 91%. Results from two more late-stage trials are due in the first half of 2027, with a US application planned for the first half of 2028.