Vaxcyte Shares Surge 56 Percent After Positive Vaccine Trial

Vaxcyte shares rose 56 percent on Monday following the announcement that its experimental 31-valent pneumococcal conjugate vaccine, VAX-31, met all prespecified primary endpoints in a late-stage study. The OPUS-1 trial enrolled 4,047 participants across approximately 30 sites in the United States.

The study compared VAX-31 against Pfizer's Prevnar 20 and Merck's Capvaxive. VAX-31 demonstrated immune responses comparable to its rivals against 28 shared strains and showed stronger responses against strain 20B and three unique strains. While the vaccine met efficacy benchmarks for all 20 strains shared with Prevnar 20, it met a less stringent threshold for two of the 19 strains shared with Capvaxive.

Vaxcyte expects results from two additional late-stage trials in the first half of 2027. The company intends to submit a U.S. marketing application in the first half of 2028.