Vaxcyte’s 31-valent pneumococcal vaccine shows non-inferior immunity to Pfizer and Merck shots in Phase 3, shares surge

Vaxcyte’s 31-valent pneumococcal candidate, VAX-31, was compared head‑to‑head with Pfizer’s Prevnar 20 and Merck’s Capvaxive in the late‑stage Opus‑1 study aimed at preventing invasive pneumococcal disease and pneumonia in adults.

The trial demonstrated non‑inferiority for all 20 serotypes covered by Prevnar 20 and for 17 of the 19 serotypes targeted by Capvaxive. VAX‑31 fell short of the non‑inferiority margin for serotypes 3 and 12F against Capvaxive, though it still met a historical lower threshold.

Safety findings indicated VAX‑31 was well tolerated, with a safety profile comparable to the approved vaccines across the age groups studied.

Investors reacted positively, sending Vaxcyte’s stock up about 57% in pre‑market trading, reaching $88.50 from a prior close of $56.48.