Vaxcyte up by a third on positive performance by its pneumococcal vaccine in trial

Shares of small vaccine developer Vaxcyte soared by almost a third on Monday to an 18-month high. The company reported positive results from a trial of a vaccine against pneumococcal infections, which can cause a range of serious diseases. At least two Wall Street analysts subsequently raised their target prices on the stock. The consensus implies a further 50% upside.

Vaxcyte shares rose nearly 31% on Monday to $73.80 per share, their highest level since March 2025. The rally began after the company reported that preliminary data showed its pneumococcal vaccine for adults had performed well in a late-stage clinical trial.

The vaccine, called VAX-31, is designed to protect against 31 strains of pneumococcal bacteria, which can cause serious illnesses including pneumonia, sepsis, meningitis, and endocarditis.

In the clinical trial, Vaxcyte compared its candidate with pharmaceutical giant Pfizer’s Prevnar 20, which protects against 20 bacterial strains, and U.S.-based Merck’s Capvaxive, which covers 21 strains. The tests showed that VAX-31 was noninferior for all 28 strains it shares with the competing products. Vaxcyte’s candidate also outperformed Prevnar 20 and Capvaxive due to its unique components.

“We believe VAX-31’s combination of broader coverage and robust immune responses, demonstrated in a trial inaugurating a more stringent noninferiority standard, sets a new benchmark for the class and gives us confidence in its potential for approval,” Vaxcyte CEO and cofounder Grant Pickering said. The company plans to submit a Biologics License Application for permission to market the vaccine to the U.S. Food and Drug Administration in the first half of 2028, supported by data from two additional studies and the completion of manufacturing readiness activities. Vaxcyte also expects results from a phase II trial of the vaccine in infants by the middle of next year, according to the press release. In many countries, pneumococcal vaccination is covered by governments or insurance programs.

Following the upbeat VAX-31 trial data, at least two Wall Street analysts raised their target prices for Vaxcyte. Guggenheim lifted its TP nearly 8% to $125 per share, implying more than 69% upside, while Needham raised its TP almost 11% to $122 per share, 65% above the current market price.

Both investment banks reiterated their “buy” ratings. Overall, the stock has seven "buy" ratings versus one "hold" recommendation. The average target price of $111 per share implies more than 50% upside. Vaxcyte’s market capitalization is up 60% since the beginning of the year.