31-Valent Pneumococcal Conjugate Vaccine Candidate Advances to Protect Children

The World Health Organization says streptococcus pneumoniae is a leading cause of vaccine-preventable deaths globally, and new, innovative vaccines are needed to curtail this disease.

To address this need, Vaxcyte, Inc. recently announced that the first study participants had been dosed in the second and final stage of the ongoing Phase 2 study of VAX-31 in healthy infants.

This clinical study evaluates the safety, tolerability, and immunogenicity of VAX-31, a 31-valent pneumococcal conjugate vaccine (PCV) candidate designed to prevent invasive pneumococcal disease (IPD) in healthy infants.

“PCVs have demonstrated the ability to deliver herd immunity to protect against devastating diseases caused by Streptococcus pneumoniae bacteria, and our technology has the potential to deliver best-in-class PCVs with broader coverage for both infants and adults,” said Jim Wassil, Executive Vice President, and Chief Operating Officer of Vaxcyte, in a press release on February 5, 2025.

“Based on the body of positive evidence from the VAX-31 and VAX-24 adult Phase 1/2 programs, we believe our carrier-sparing platform has the potential to set a new standard in disease coverage.”

The Company expects to share topline data from the primary three-dose immunization series of the study in mid-2026, followed by topline data from the booster dose approximately nine months later.

In children under five. Pneumococci also cause over 50% of all cases of bacterial meningitis in the U.S. And pneumococcal pneumonia is estimated to result in approximately 150,000 hospitalizations yearly. 

And Streptococcus pneumoniae is among the top antibiotic-resistant pathogens to be urgently addressed, and the U.S. CDC lists drug-resistant  Streptococcus pneumoniae as a “serious threat.”

This indicates the need for expanding PCV vaccinations is essential.