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News
Vaxcyte's experimental pneumococcal vaccine VAX-31 matched or outperformed rival shots from Pfizer and Merck in a late-stage trial, sending the company's stock soaring 57%. The vaccine showed comparable immune responses across 28 shared bacterial strains and stronger responses against strains unique to VAX-31, with a clean safety profile. Analysts say it's well-positioned to capture a major slice of the multi-billion-dollar adult vaccine market.
Vaxcyte's experimental pneumococcal vaccine, VAX-31, just had a standout moment in its late-stage clinical trial — and Wall Street noticed. The vaccine generated immune responses at least comparable to Pfizer's Prevnar 20 and Merck's Capvaxive across 28 shared bacterial strains (serotypes), while also producing stronger responses against three strains unique to VAX-31 and against strain 20B. The safety profile was consistent across all age groups studied, with no serious adverse events linked to the vaccine.
There were a couple of minor caveats: VAX-31 missed the trial's stricter benchmark for two strains shared with Capvaxive, though it still met a historical threshold. Analysts at Leerink Partners noted this likely reflects a tougher trial standard rather than a regulatory red flag.
By the Numbers:
Why it matters: Pneumococcal disease — which can cause pneumonia, meningitis, and bloodstream infections — is a serious threat, especially for older adults. A new competitive vaccine option could reshape the adult immunization landscape and potentially improve access and outcomes in a market currently dominated by Pfizer and Merck.
