Vaxcyte shares surge as pneumococcal vaccine succeeds in late-stage trial
PCVX•Vaxcyte said its experimental VAX-31 vaccine generated immune responses comparable to rival vaccines in a late-stage study, and its shares rose 57% in morning trading. The company expects results from two other late-stage trials in the first half of 2027 and plans to submit a U.S. marketing application in the first half of 2028.
1. Trial results
VAX-31 produced immune responses at least comparable to Pfizer’s Prevnar 20 and Merck’s Capvaxive against the 28 bacterial strains shared with one or both vaccines. It produced stronger responses against three strains unique to VAX-31 and strain 20B. Vaxcyte said the vaccine had a consistent safety profile across the age groups studied, with no serious adverse events considered related to the vaccines.
2. Comparisons and outlook
VAX-31 met the study benchmark for all 20 strains it shares with Prevnar 20 and 17 of 19 shared with Capvaxive. For the other two Capvaxive-shared strains, it missed the stricter benchmark but met a historical threshold. Leerink Partners analyst David Risinger said the miss against Capvaxive on serotype 3 reflected a tougher trial standard and was unlikely to have regulatory significance. Jefferies analyst Roger Song said the results hit the “blue-sky” case and that VAX-31 was poised to take significant share of the $3 billion to $6 billion-plus adult vaccine market. Vaxcyte expects results from two other late-stage trials in the first half of 2027 and plans to submit a U.S. marketing application in the first half of 2028.
