Vaxcyte's Pneumococcal Conjugate Vaccine Advances: VAX-31 Phase 3 Progress and Pipeline Expansion

Vaxcyte, Inc. (PCVX) announced significant milestones for its lead pneumococcal conjugate vaccine candidate, VAX-31, along with full-year 2025 financial results. The company’s focus on expanding serotype coverage through its vaccine innovation is positioning the organization as a key player in preventing invasive pneumococcal disease and pneumonia across multiple age groups.

Phase 3 Adult Trials Progressing on Schedule

VAX-31, a 31-valent pneumococcal conjugate candidate, is advancing through three pivotal Phase 3 trials—OPUS-1, OPUS-2, and OPUS-3—with thousands of participants enrolled to assess safety, tolerability, and immunogenicity. The vaccine is being evaluated against current treatment standards, including Prevnar 20 and Capvaxine. The company received FDA Breakthrough Therapy Designation for VAX-31 in the adult population, underscoring regulatory recognition of the vaccine’s potential.

Vaxcyte anticipates topline data from OPUS-1 in the fourth quarter of 2026, with readouts from the remaining trials expected in the first half of 2027. The broad serotype coverage of VAX-31—designed to address more serotypes than any existing pneumococcal conjugate vaccine in clinical development—represents a potential advancement in protection against invasive pneumococcal disease.

Infant Study Enrollment Complete, Broader Pipeline in Motion

In parallel, Vaxcyte completed enrollment for its Phase 2 infant dose-finding study, with topline results anticipated in the first half of 2027. This milestone demonstrates the company’s commitment to advancing pneumococcal conjugate vaccine solutions across the lifespan.

Beyond VAX-31, Vaxcyte is progressing a diversified vaccine portfolio. VAX-24, a 24-valent pneumococcal conjugate option for infants, is advancing through Phase 2 development with coverage designed to exceed marketed infant vaccines. VAX-XL, a third-generation candidate in early development, leverages carrier-sparing conjugation technology for enhanced coverage. The company is also pursuing VAX-A1 for Group A Streptococcus, with a Phase 1 adult study targeted for 2026, and VAX-GI, a preclinical candidate addressing Shigella infections.

Manufacturing Facility Completion Supports Global Commercialization

Vaxcyte concluded 2025 with $2.4 billion in cash, cash equivalents, and investments. The company’s net loss for Q4 2025 reached $246.5 million compared to $137.1 million in the prior year quarter. Full-year net loss expanded to $766.6 million versus $463.9 million in 2024.

A significant portion of 2025 expenditures—$21.8 million in Q4 alone—supported construction of the company’s dedicated Lonza manufacturing facility. Total buildout expenditures reached $335.4 million by year-end, with completion achieved in Q1 2026 within the original $350 million budget. This facility is intended to enable global commercialization of Vaxcyte’s pneumococcal conjugate vaccine program and represents a critical infrastructure investment.

Market Performance

PCVX has fluctuated between $27.66 and $83.33 over the past year. The stock closed Tuesday’s session at $61.35, up 1.81%, before declining 2.97% to $59.53 in overnight trading Wednesday.