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News
Vaxcyte's experimental pneumococcal vaccine, VAX-31, matched or outperformed rival vaccines from Pfizer and Merck in a late-stage trial, sending the company's stock soaring 57%. The vaccine demonstrated comparable immune responses across 28 shared bacterial strains and stronger responses against three unique strains, 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 VAX-31 is making waves in the pneumococcal vaccine space. The experimental vaccine matched or exceeded immune responses generated by Pfizer's Prevnar 20 and Merck's Capvaxive across 28 shared bacterial strains (serotypes) in a late-stage clinical trial — and even outperformed both rivals against three strains unique to VAX-31 and against strain 20B. The news sent Vaxcyte's shares up 57% in a single morning.
The safety picture also looked solid — no serious adverse events were linked to the vaccine across the age groups studied. There was one minor hiccup: VAX-31 missed the trial's stricter benchmark against two strains shared with Capvaxive (including serotype 3), though it still met a historical threshold. Analysts at Leerink Partners noted this likely reflects a tougher trial standard rather than a real regulatory concern.
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, highly effective vaccine entering the market could expand protection options and shake up a competitive vaccine landscape.
