Pfizer’s 25-valent pneumococcal vaccine shows strong results in infant trial as it vies for a launch window

What was strong about the Phase II data?

Pfizer presented results from the Phase II infant trial of its 25-valent pneumococcal conjugate vaccine candidate, 25vPnC, at IDWeek 2026. Goldman Sachs considers the overall data strong.
After the 4th dose, all 20 serotypes shared with the existing 20-valent vaccine PCV20 met the previously used 2-fold noninferiority criterion. The comparison examined whether immune responses to shared serotypes can be maintained when coverage is expanded.
Pfizer’s modeling predicts that more than 22 of the 25 serotypes will meet the more stringent 1.5-fold noninferiority criterion in a large Phase III trial. In addition, 25vPnC produced an enhanced immune response to serotype 3.

Pfizer’s Prevnar vaccine business is under competitive pressure: Merck’s Capvaxive has entered the adult market, and Vaxcyte’s VAX-31 could also enter the competition in the future.
The currently larger infant market is dominated by Pfizer’s Prevnar20. Goldman Sachs sees the 25vPnC data as a step in Pfizer’s defense of this market; Vaxcyte expects to release Phase II infant data for VAX-31 in the first half of 2027.
Pfizer has launched the Phase III program for 25vPnC. Goldman Sachs believes that, if development succeeds, it could reach the market before VAX-31 receives its infant indication; it remains uncertain whether the two products will be directly compared in clinical trials.

Goldman Sachs expects Phase III data for 25vPnC could be released from late 2027 to early 2028. Pfizer has not yet provided guidance on the timing of the data readout. Goldman Sachs is also watching for further details on the earnings call on 3 November.
For adult products, Pfizer plans to advance its fifth-generation 35-valent vaccine candidate into clinical development by the end of 2026, subject to agreement with regulators; Phase II adult data for VAX-31 are expected in the first half of 2027.

Goldman Sachs maintained its Neutral rating on Pfizer and its 12-month price target of 26 dollars, 13.4% below the 23 October 2026 closing price of 30.03 dollars. The target is based on a multiple of 9 times adjusted earnings per share for the forward rolling 5th through 8th quarters.
The bank takes a conservative view of the vaccine business’s commercial and regulatory prospects: stabilization could improve its earnings forecasts and market sentiment; if the regulatory and commercial outlook is worse than expected, vaccine business forecasts could be lowered further.