Vaxcyte shares closed at $65.27 on October 15, 2026, retaining a roughly 54% gain from October 27, 2025, despite retreating from their October peak. The clinical-stage vaccine developer announced positive pivotal Phase 3 results for its investigational pneumococcal vaccine VAX-31 on October 5, with further adult and infant study results expected in 2027.
Key Takeaways
- Shares remained above their October 2025 level but below the October 5, 2026, intraday high of $90.75.
- VAX-31 met all prespecified primary endpoints in OPUS-1, although two individual comparisons against PCV21 missed the stricter noninferiority threshold.
- Vaxcyte expects additional adult trial results in the first half of 2027 ahead of a planned U.S. application in the first half of 2028.
Table of Contents
- Vaxcyte shares pull back from their October peak
- Positive primary results include a comparator caveat
- Further trial readouts precede a planned filing
- Conclusion
Vaxcyte shares pull back from their October peak
The October 15 closing price compares with $42.30 on October 27, 2025. At the October 5 intraday high of $90.75, the gain from that starting point had reached approximately 115%. Those returns cover a period beginning in October 2025, not calendar-year 2026.
The subsequent retreat left shares about 28% below that intraday peak. While the high occurred on the date of the OPUS-1 announcement, the available information does not establish a single cause for either the rally or the pullback.
The clinical program has advanced through several milestones: first participants were dosed in OPUS-1 in December 2025 and OPUS-3 in February 2026, followed by completion of enrollment in OPUS-1 and OPUS-2 in March.
| Item | Details |
|---|---|
| OPUS-1 enrollment | 4,047 participants at approximately 30 U.S. sites. |
| Older-adult cohort | 3,572 participants aged 50 and older. |
| Younger-adult cohort | 475 participants aged 18–49. |
| Assessment timing | Immune responses assessed one month after vaccination; safety and tolerability assessed for six months. |
Positive primary results include a comparator caveat
Vaxcyte’s OPUS-1 topline results announcement said VAX-31 met all prespecified primary endpoints across the age groups studied. The 31-valent candidate is being developed to prevent invasive pneumococcal disease and pneumococcal pneumonia; it remains investigational.
In adults aged 50 and older, all 28 vaccine serotypes shared with PCV20 and/or PCV21 met the prespecified primary noninferiority criteria. The three serotypes unique to VAX-31 and cross-reactive serotype 20B met the superiority criterion. Vaxcyte also reported a safety profile similar to the comparator vaccines.
The individual comparator analyses require a distinction. VAX-31 met the stricter noninferiority threshold for all 20 serotypes shared with PCV20, but for 17 of 19 shared with PCV21. Serotypes 3 and 12F missed that threshold while meeting the historical, less stringent threshold.
These findings concern immune responses and safety rather than a direct measurement of reduced disease cases. Vaxcyte said it expects the comparison with PCV21 to be a particular focus of FDA review.
Further trial readouts precede a planned filing
Vaxcyte expects safety, tolerability and immunogenicity results from the OPUS-2 and OPUS-3 adult Phase 3 trials in the first half of 2027. It plans a biologics license application submission in the first half of 2028, subject to FDA review.
The company also expects infant Phase 2 results covering both the primary three-dose series and booster dose by the end of the first half of 2027. Outside pneumococcal vaccines, adult Phase 1 results for its Group A Streptococcus candidate, VAX-A1, are expected in the second half of 2027. These are development targets, not completed results or regulatory approvals.
Conclusion
The next scheduled clinical checkpoints are the OPUS-2 and OPUS-3 results in the first half of 2027. Those readouts will add to the evidence behind Vaxcyte’s planned application, while OPUS-1’s individual PCV21 comparisons remain an important qualification to its positive primary results.
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