Vaxcyte's pneumococcal vaccine meets trial goals shares surge

Vaxcyte's experimental pneumococcal vaccine, VAX-31, has met its primary goals in a late-stage study involving adults aged 50 and older. The news sent the company's shares soaring by 91% in premarket trading on Monday. Pneumococcal disease, which can lead to serious conditions like pneumonia and meningitis, poses a significant risk to older adults.

The vaccine demonstrated immune responses at least comparable to those of Pfizer's Prevnar 20 and Merck's Capvaxive against 28 bacterial strains shared with one or both rival vaccines. Additionally, VAX-31 produced stronger immune responses against three strains unique to it and against strain 20B. The vaccine also met the study's efficacy benchmark for all 20 strains it shares with Prevnar 20 and for 17 of 19 strains shared with Capvaxive.

Vaxcyte reported that VAX-31 had a consistent safety profile across the age groups studied, with no serious adverse events related to the vaccine. For two strains shared with Capvaxive, VAX-31 missed the study's stricter benchmark but met a less stringent threshold historically used in vaccine studies.

The company expects results from two other late-stage trials in the first half of 2027 and plans to submit a US marketing application for VAX-31 in the first half of 2028.