Vaxcyte (PCVX) said Monday its 24-valent pneumococcal conjugate vaccine candidate VAX-24, designed to prevent invasive pneumococcal disease, showed substantial immune response in healthy infants after three doses.

The phase 2 trial showed that the vaccine was well-tolerated and demonstrated a safety profile similar to Prevnar 20 across all doses studied in 802 healthy infants.

Based on the findings, the company said the mid dose will be the basis for advancing an optimized dose formulation to a potential phase 3 program.

Pending the results of its VAX-31 phase 2 study expected in mid-2026, the company said it plans to initiate an infant phase 3 study with one of the two vaccine candidates.