Core Insights - Vaxcyte, Inc. is advancing its VAX-31 infant Phase 2 randomized, dose-finding study to the final stage, focusing on a 31-valent pneumococcal conjugate vaccine designed to prevent invasive pneumococcal disease (IPD) in infants [1][2][3] - The VAX-31 Optimized Dose aims to elicit stronger immune responses in infants, with the majority of serotypes dosed at 4.4mcg and the balance at 3.3mcg, potentially covering approximately 92% of IPD and 93% of acute otitis media in U.S. children under five [1][3][6] - The company plans to release topline data from the primary immunization series and booster dose by the end of the first half of 2027 [1][2] Company Overview - Vaxcyte is a clinical-stage vaccine innovation company focused on developing high-fidelity vaccines to combat bacterial diseases [1][8] - The company is also developing VAX-24, a 24-valent PCV candidate, which aims to cover more serotypes than any existing infant PCV on the market [8][9] - Vaxcyte utilizes the XpressCF platform for cell-free protein synthesis, enhancing its ability to produce complex vaccines [9] Study Details - The VAX-31 infant Phase 2 study is a randomized, double-blind, active-controlled trial evaluating safety, tolerability, and immunogenicity compared to Prevnar 20 (PCV20) [4][10] - The study will enroll approximately 900 participants, including those previously in the Low Dose arm, and will assess immune responses through serotype-specific immunoglobulin G (IgG) seroconversion rates [2][10] - The study consists of three stages, with the first stage completed and the second stage modified to include the new Optimized Dose arm [4][10] Disease Context - Pneumococcal disease, caused by Streptococcus pneumoniae, is a leading cause of vaccine-preventable deaths among children under five, with significant morbidity and mortality [5][6] - The disease can lead to severe conditions such as meningitis and bacteremia, highlighting the urgent need for a broader-spectrum vaccine [5][6] Regulatory Status - The FDA has expanded the Breakthrough Therapy designation for VAX-31 to include the prevention of pneumonia caused by Streptococcus pneumoniae, indicating potential substantial improvement over existing therapies [7]