Vaxcyte Doses First Participants in the OPUS Phase 3, Noninferiority Trial Evaluating VAX-31 for the Prevention of Invasive Pneumococcal Disease and Pneumonia in Adults

Rhea-AI Summary

Vaxcyte (NASDAQ: PCVX) dosed the first participants in the OPUS Phase 3 pivotal, noninferiority trial of VAX-31 for prevention of invasive pneumococcal disease (IPD) and pneumonia in adults. The trial is designed in alignment with the FDA and will enroll ~4,000 participants with topline safety, tolerability and immunogenicity results expected in Q4 2026. VAX-31 is designed to cover ~95% of IPD and ~88% of pneumococcal pneumonia in U.S. adults 50+, and may provide an incremental 14–34% broader IPD coverage and 19–31% broader pneumonia coverage versus current standard-of-care vaccines. Results will support planned BLA timelines and additional Phase 3 studies in 2026 with readouts in 2027.

Positive

• First participants dosed in the OPUS Phase 3 trial
• Trial design finalized in alignment with the FDA
• Planned enrollment of approximately 4,000 participants
• Topline results expected in Q4 2026
• VAX-31 designed to cover ~95% IPD and ~88% pneumonia
• Potential incremental coverage: IPD +14–34%, pneumonia +19–31%

Negative

• Regulatory approval depends on successful Phase 3 results
• Topline and additional Phase 3 readouts not expected until 2026–2027

Key Figures

OPUS Phase 3 enrollment approximately 4,000 participants Adult OPUS Phase 3 noninferiority trial design

Adult IPD coverage ~95% VAX-31 coverage of invasive pneumococcal disease in U.S. adults 50+

Adult pneumonia coverage ~88% VAX-31 coverage of pneumococcal pneumonia in U.S. adults 50+

Incremental IPD coverage 14–34% broader VAX-31 vs standard-of-care adult vaccines

Incremental pneumonia coverage 19–31% broader VAX-31 vs standard-of-care adult vaccines

Shared serotypes 28 serotypes Serotypes shared with PCV21 and/or PCV20 for noninferiority testing

Noninferiority margin OPA GMR lower bound 0.667 Primary immunogenicity objective vs PCV21/PCV20

Superiority threshold OPA GMR lower bound 2.0 For three unique VAX-31 serotypes and serotype 20B

Market Reality Check

$44.34 Last Close

Volume Volume 1,051,818 is below the 20-day average of 1,511,600 (relative volume 0.7x). normal

Technical Shares at $46.48 are trading above the 200-day MA at $40.99 and sit 50.87% below the 52-week high.

Peers on Argus 1 Up

Peer moves are mixed: KRYS up 5.35%, ACAD up 2.58%, ACLX up 2.4%, while ARWR is down 2.4%. Momentum scanner only flags ACLX with a strong 12.52% move without news, suggesting today’s PCVX setup looks more stock-specific than sector-driven.

Historical Context

Date	Event	Sentiment	Move	Catalyst
Nov 04	Earnings & pipeline	Positive	-2.5%	Strong cash of $2.67B and positive VAX‑24/VAX‑31 infant data with extended runway.
Sep 30	Manufacturing deal	Positive	+4.0%	Up to $1B Thermo Fisher fill‑finish agreement expanding U.S. commercial capacity.
Sep 30	Peer management news	Neutral	+4.0%	Tentarix executive hires mentioning a Vaxcyte co‑founder but no direct PCVX catalyst.
Sep 03	Infant trial advance	Positive	+1.7%	VAX‑31 infant Phase 2 advancing to final stage with ~900 participants and broad coverage.
Aug 06	Earnings update	Negative	-9.1%	Higher R&D, net loss of $166.6M and focus on PCV programs despite strong cash.

Pattern Detected

PCVX has often seen aligned price moves around strategic and clinical updates, with one notable divergence on a positive Q3 update.

Recent Company History

Over the last six months, Vaxcyte has advanced multiple pneumococcal programs while strengthening finances. Q2 and Q3 2025 updates highlighted cash of $2.8B–$2.67B and runway into mid‑2028, alongside higher R&D spend and net losses. Clinically, VAX‑31 infant Phase 2 progressed to its final stage (~900 participants), and the adult Phase 3 start was guided for Dec 2025. A long-term U.S. fill-finish agreement of up to $1B also boosted commercial readiness. Today’s adult Phase 3 dosing marks the planned transition into pivotal development for VAX‑31.

Market Pulse Summary

This announcement details first dosing in the OPUS adult Phase 3 noninferiority trial for VAX‑31, targeting ~4,000 participants and aiming for broad serotype coverage and potential best‑in‑class status. It builds on earlier VAX‑31 and VAX‑24 infant data and prior FDA interactions. Investors may watch for the planned topline readout in Q4 2026, additional Phase 3 studies in 2026–2027, and how these align with the company’s runway into mid‑2028 and manufacturing build‑out.

Key Terms

noninferiority medical

"OPUS Phase 3 pivotal, noninferiority trial evaluating VAX-31 for the prevention"

Noninferiority is a type of clinical trial comparison designed to show a new treatment is not meaningfully worse than an existing standard by a pre-set margin. For investors, it matters because a successful noninferiority result can allow a new product to enter the market and compete with established options, similar to proving a new model performs close enough to a trusted one to win customers and drive revenue.

biologics license application regulatory

"results ... are expected to serve as the cornerstone of the VAX-31 Biologics License Application (BLA)"

A biologics license application is a formal request submitted to regulatory authorities seeking approval to market a new biological medicine, such as vaccines or treatments made from living organisms. It is a comprehensive review process that evaluates the safety, effectiveness, and manufacturing quality of the product. For investors, receiving approval signals that a biological therapy can be sold to the public, potentially leading to revenue growth and market success.

immunogenicity medical

"Topline safety, tolerability and immunogenicity results from the OPUS trial"

Immunogenicity is the ability of a substance, such as a vaccine or medication, to provoke an immune response in the body. It matters to investors because high immunogenicity can affect the effectiveness and safety of a product, potentially leading to increased costs or regulatory challenges. Understanding immunogenicity helps assess the long-term viability and market potential of pharmaceutical and biotech investments.

opsonophagocytic activity medical

"95% confidence interval (CI) for the opsonophagocytic activity (OPA) geometric mean ratio"

A lab measure of how well antibodies can tag and help immune cells swallow and destroy a specific germ, like testing whether the body’s defense system can actually neutralize a threat rather than just recognize it. Investors care because higher opsonophagocytic activity suggests a vaccine or antibody therapy is likely to be effective in the real world, influencing clinical value, regulatory decisions, and commercial potential.

geometric mean ratio medical

"95% confidence interval (CI) for the opsonophagocytic activity (OPA) geometric mean ratio (GMR)"

The geometric mean ratio is the result of dividing one geometric mean by another to compare proportional or multiplicative quantities, such as compound returns or growth rates. It matters to investors because it captures typical percentage changes when values multiply over time (like compound interest) and is less distorted by extreme values than an ordinary average, so it gives a truer sense of relative performance between investments or periods.

confidence interval technical

"noninferiority if the lower bound of the two-sided 95% confidence interval (CI)"

An interval estimate that shows a range of values within which a true number (like a company’s expected earnings, a projected return, or a model input) is likely to lie, together with a stated level of confidence in that range. For investors it turns a single point forecast into a band—like a weather forecast saying 60–70°F instead of just 65°F—making uncertainty explicit so you can judge risk and size positions more sensibly.

serotypes medical

"for the 28 serotypes shared with one or both comparators and 2) superiority"

Serotypes are distinct variations within a species of bacteria or viruses defined by different surface markers that cause the immune system to react differently. For investors, serotypes matter because they determine whether a vaccine, diagnostic test or therapeutic will work across the full range of strains, influence development time and regulatory hurdles, and shape market size and competitive positioning—like different car models that require different keys or parts.

pneumococcal conjugate vaccine medical

"next-generation VAX-31 PCV is intended to provide the broadest coverage"

A pneumococcal conjugate vaccine is a shot that trains the immune system to recognize and fight Streptococcus pneumoniae bacteria, which cause pneumonia, meningitis and bloodstream infections. The “conjugate” part means pieces of the bacteria are chemically linked to a harmless carrier so the body learns more effectively—like pinning a printed photo to a solid backing to make it easier to display. Investors care because demand, regulatory approvals, pricing, patent protection and public‑health programs drive sales, company valuation and long‑term revenue in the vaccine market.

AI-generated analysis. Not financial advice.

Trial Design Finalized in Consultation and Alignment with U.S. Food and Drug Administration 

Study Designed to Establish a New Standard for Adult Pneumococcal Conjugate Vaccines Through Head-to-Head Safety, Tolerability and Immunogenicity Comparisons of VAX-31 with Capvaxive (PCV21) and Prevnar 20 (PCV20), the Current Standards of Care

Company Expects to Report Topline Safety, Tolerability and Immunogenicity Data for OPUS Phase 3, Noninferiority Trial in the Fourth Quarter of 2026 and Initiate Additional Phase 3 Studies in 2026 with Readouts in 2027, Supporting Planned BLA Submission

VAX-31 is Designed to Cover ~95% of Invasive Pneumococcal Disease (IPD) and ~88% of Pneumococcal Pneumonia in U.S. Adults Aged 50+, with Potential to Provide an Incremental 14-34% Broader IPD Coverage and 19-31% Broader Pneumonia Coverage than Standard-of-Care Vaccines

VAX-31 Aims to Advance Adult Pneumococcal Protection by Maintaining Critical Pressure on Both Currently Circulating and Long-Established, Historically Disease-Causing Serotypes, While Maintaining or Improving Immune Responses

SAN CARLOS, Calif., Dec. 08, 2025 (GLOBE NEWSWIRE) -- Vaxcyte, Inc. (Nasdaq: PCVX), a clinical-stage vaccine innovation company, today announced that the first participants were dosed in the OPUS (OPA-based Pivotal U.S. Study) Phase 3 pivotal, noninferiority trial evaluating VAX-31 for the prevention of invasive pneumococcal disease (IPD) and pneumonia in adults. The design of the trial, which is expected to enroll approximately 4,000 participants, was finalized in consultation and alignment with the U.S. Food and Drug Administration (FDA). Topline safety, tolerability and immunogenicity results from the OPUS trial, which are expected to serve as the cornerstone of the VAX-31 Biologics License Application (BLA), are anticipated in the fourth quarter of 2026.

Building on the unprecedented results from the Company’s VAX-31 adult Phase 1/2 study, which demonstrated both broader serotype coverage and stronger overall immune responses than Prevnar 20 (PCV20), the OPUS trial represents the next step in setting a new standard for adult pneumococcal vaccines. This trial is evaluating the safety, tolerability and immune responses of VAX-31 in adults aged 50 and older through direct, head-to-head comparisons with both Capvaxive (PCV21) and PCV20, the current standard-of-care pneumococcal conjugate vaccines (PCVs), with the objective of establishing a best-in-class profile for VAX-31.

The key primary immunogenicity objectives of the OPUS trial are to demonstrate 1) noninferiority if the lower bound of the two-sided 95% confidence interval (CI) for the opsonophagocytic activity (OPA) geometric mean ratio (GMR) of VAX-31 exceeds 0.667 compared with PCV21 and/or PCV20 for the 28 serotypes shared with one or both comparators and 2) superiority if the lower bound of the two-sided 95% CI of the OPA GMR exceeds 2.0 for the three serotypes unique to VAX-31 and serotype 20B versus the comparator vaccines. The trial is also evaluating the safety, tolerability and immune responses of VAX-31 in adults aged 18-49. Key secondary immunogenicity objectives are included to evaluate VAX-31 based on additional measures of noninferiority, superiority and statistically greater immune responses.

“The initiation of our adult Phase 3 program marks a major milestone in the development of VAX-31 as the program enters the final phase of clinical development, advancing toward potential licensure,” said Grant Pickering, Chief Executive Officer and Co-founder of Vaxcyte. “On the strength of the unprecedented results from our VAX-31 Phase 1/2 study in adults and our carrier-sparing platform, we are uniquely positioned to set a new standard by which future adult pneumococcal vaccines will be measured. Through this program, we are aiming to expand the breadth of disease and serotype coverage while ensuring immunogenicity levels remain high to ensure durable protection. To this end, VAX-31 has the potential to provide a 14-34% increase in coverage for IPD and a 19-31% increase in coverage for pneumococcal pneumonia over current standard-of-care vaccines for U.S. adults. We expect to announce topline data from the OPUS noninferiority trial in the fourth quarter of 2026 and the results of additional Phase 3 studies in 2027, keeping our timelines to both potential BLA filing and U.S. launch on track. Consistent with precedent, we would also plan to generate post-licensure real-world evidence in the adult population.”

“Pneumococcal disease remains one of the most significant vaccine-preventable threats in adults, with a growing prevalence of disease from serotypes not covered by existing vaccines,” said Jim Wassil, Executive Vice President and Chief Operating Officer of Vaxcyte. “By leveraging our carrier-sparing, site-specific conjugation technology and deep understanding of adult immunobiology, our next-generation VAX-31 PCV is intended to provide the broadest coverage by maintaining critical pressure on both currently circulating as well as long-established, historically disease-causing serotypes that remain controlled largely because of ongoing vaccination.”

About OPUS, the VAX-31 Adult Pivotal Phase 3 Noninferiority Trial (n~4,000)
The pivotal Phase 3 study of VAX-31 is a randomized, double-blind, active-controlled clinical trial evaluating the safety, tolerability and immunogenicity of the High Dose formulation of VAX-31 in which all serotypes are dosed at 3.3 mcg, except serotypes 1, 5 and 22F which are dosed at 4.4 mcg, in healthy, pneumococcal-naïve¹ U.S. adults aged 50 years and older with a separate cohort of adults aged 18-49 years. The study is being conducted at approximately 50 sites in the United States.

Participant Overview (age and randomization)

• Adults aged ≥50 years (n~3,560): Participants in this age group will be randomized 1:1:1 to receive a single dose of VAX-31, PCV21 or PCV20 on Day 1.
• Adults aged 18-49 years (n~440): Participants in this age group will be randomized 3:1 to receive a single dose of VAX-31 or PCV20 on Day 1, with PCV20 serving as the safety comparator.

For all participants, safety and tolerability will be assessed for six months following initial vaccination of VAX-31, PCV21 or PCV20.

Immunogenicity Analyses (to occur 1-month post vaccination)
Primary immunogenicity objectives:

• Noninferiority of VAX-31 compared with PCV21 and/or PCV20 for the 28 serotypes shared with either or both comparator vaccines in adults aged 50 years and older (criterion: lower bound (LB) of the two-sided 95% confidence interval (CI) of the OPA GMR is >0.667).
• Superiority of VAX-31 compared with PCV21 or PCV20 for the three serotypes unique to VAX-31 (2, 7C and 20C) and for serotype 20B in adults aged 50 years and older (criterion: LB of the two-sided 95% CI of the OPA GMR is >2.0).
• Noninferiority of VAX-31 immune responses in adults aged 18-49 years compared with those in adults aged 50-64 years (criterion: LB of the two-sided 95% CI of the OPA GMR is >0.667).
  

Key secondary immunogenicity objectives:

• Noninferiority of VAX-31 compared with both PCV21 and PCV20 for the 11 serotypes common to all three vaccines in adults aged 50 years and older (criterion: LB of the two-sided 95% CI of the OPA GMR is >0.5).
• Statistically greater immune responses elicited by VAX-31 compared with those elicited by PCV21 or PCV20 for the 28 shared serotypes in adults aged 50 years and older (criterion: LB of the two-sided 95% CI of the OPA GMR is >1.0).
• Superiority of VAX-31 compared with PCV20 for the eight serotypes common to VAX-31 and PCV21 but not included in PCV20 in adults aged 50 years and older (criterion: LB of the two-sided 95% CI of the OPA GMR is >2.0).
• Superiority of VAX-31 compared with PCV21 for the nine serotypes common to VAX-31 and PCV20 but not included in PCV21 in adults aged 50 years and older (criterion: LB of the two-sided 95% CI of the OPA GMR is >2.0).

VAX-31 Serotypes vs. Comparators:

• VAX-31 serotypes (31): 1, 2, 3, 4, 5, 6A, 6B, 7C, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15A, 15B, 16F, 17F, 18C, 19A, 19F, 20C, 22F, 23A, 23B, 23F, 31, 33F, 35B
• Serotypes common to VAX-31, PCV21 and PCV20 (11): 3, 6A, 7F, 8, 10A, 11A, 12F, 15B, 19A, 22F, 33F
• Serotypes common to VAX-31 and PCV20 but not in PCV21 (9): 1, 4, 5, 6B, 9V, 14, 18C, 19F, 23F
• Serotypes common to VAX-31 and PCV21 but not in PCV20 (8): 9N, 15A, 16F, 17F, 23A, 23B, 31, 35B
• Serotypes unique to VAX-31 (3): 2, 7C, 20C (20B is also being evaluated)
  

Anticipated Key PCV Program Milestones
Vaxcyte is advancing the clinical development of its PCV programs with several anticipated key upcoming milestones:

PCV Franchise Adult Indication

VAX-31

• Announce topline safety, tolerability and immunogenicity data for the OPUS Phase 3 pivotal, noninferiority study in the fourth quarter of 2026.
• Initiate remaining Phase 3 studies in 2026 and announce data from these studies in 2027 (details of each study to be announced upon commencement).

PCV Franchise Infant Indication

VAX-31

• Announce topline safety, tolerability and immunogenicity data for the VAX-31 infant Phase 2 randomized, dose-finding study from both the primary three-dose immunization series and booster dose either sequentially or together by the end of the first half of 2027.
  

About Pneumococcal Disease
Pneumococcal disease (PD) is an infection caused by Streptococcus pneumoniae bacteria. It can result in IPD, including meningitis and bacteremia, and non-invasive PD, including pneumonia, otitis media and sinusitis. In the United States, pneumococcal pneumonia is estimated to result in over 150,000 hospitalizations each year. Streptococcus pneumoniae is among the World Health Organization’s top antibiotic-resistant pathogens to be urgently addressed, and the U.S. CDC lists drug-resistant Streptococcus pneumoniae as a “serious threat.” In children under five, Streptococcus pneumoniae is the leading cause of vaccine-preventable deaths globally. Pneumococci also cause over 50% of all cases of bacterial meningitis in the United States. Antibiotics are used to treat PD, but some strains of the bacteria have developed resistance to treatments. The morbidity and mortality due to PD are significant, particularly for young children and older adults, underscoring the need for a broader-spectrum vaccine.

About VAX-31
VAX-31, a 31-valent PCV candidate being evaluated in a Phase 3 adult clinical program and in a Phase 2 infant clinical program, is designed to prevent IPD, which is especially serious in infants, young children, older adults and those with immune deficiencies or certain chronic health conditions. IPD is associated with high case-fatality rates, antibiotic resistance and meningitis. VAX-31 is the broadest-spectrum PCV candidate in the clinic today and has the potential to provide protection against both currently circulating and historically prevalent serotypes.

VAX-31 is designed to increase coverage, in a single vaccine, to approximately 95% of IPD and approximately 88% of pneumococcal pneumonia circulating in adults in the United States aged 50 and older. This disease coverage has the potential to result in VAX-31 providing an incremental 14-34% of coverage for IPD and an incremental 19-31% of coverage for pneumococcal pneumonia over current standard-of-care adult PCVs. In U.S. children, it is designed to cover approximately 92% of IPD² and approximately 96% of acute otitis media³ due to Streptococcus pneumoniae. This disease coverage has the potential to result in VAX-31 providing an incremental 23-44% of coverage for IPD and an incremental 35-62% of coverage for otitis media over current standard-of-care infant PCVs.

In May 2025, the FDA expanded the Breakthrough Therapy designation (BTD) for VAX-31 to include the prevention of pneumonia caused by Streptococcus pneumoniae in addition to the prevention of IPD in adults based on the positive topline results from the VAX-31 adult Phase 1/2 study indicating that VAX-31 may demonstrate substantial improvement over existing therapies. In this study, the VAX-31 High Dose was observed to be well tolerated, demonstrated a safety profile similar to PCV20 and showed robust OPA immune responses for all 31 serotypes. With the VAX-31 High Dose, all 11 incremental serotypes unique to VAX-31, and not in PCV20, met the superiority criteria,⁴ and it delivered greater average OPA immune responses for 18 of the 20 serotypes in common with PCV20, and seven of these serotypes achieved statistically higher immune responses.⁵

About Vaxcyte
Vaxcyte is a vaccine innovation company engineering high-fidelity vaccines to protect humankind from the consequences of bacterial diseases. VAX-31, a 31-valent PCV candidate being evaluated in a Phase 3 adult clinical program and in a Phase 2 infant clinical program, is being developed for the prevention of IPD and is the broadest-spectrum PCV candidate in the clinic today. VAX-24, a 24-valent PCV candidate, is designed to cover more serotypes than any infant PCV on-market. VAX-31 and VAX-24 are designed to improve upon standard-of-care PCVs by covering the serotypes in circulation that cause a significant portion of IPD and are associated with high case-fatality rates, antibiotic resistance and meningitis, while maintaining coverage of previously circulating strains. VAX-XL, in earlier-stage development, also leverages the Company’s carrier-sparing, site-specific conjugation technology with the aim of further expanding coverage to deliver the broadest-spectrum candidate in the Company’s PCV franchise.

Vaxcyte is re-engineering the way highly complex vaccines are made through XpressCF®, its cell-free protein synthesis platform exclusively licensed from Sutro Biopharma, Inc. Unlike conventional cell-based approaches, the Company’s system for producing difficult-to-make proteins and antigens is intended to accelerate its ability to develop high-fidelity vaccines with enhanced immunological benefits. Vaxcyte’s pipeline also includes VAX-A1, a prophylactic vaccine candidate designed to prevent Group A Strep infections, and VAX-GI, a vaccine candidate designed to prevent Shigella. For more information, visit www.vaxcyte.com.

Forward-Looking Statements 
This press release contains forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. These statements include, but are not limited to, statements related to the potential benefits of Vaxcyte’s carrier-sparing platform and PCV candidates, including breadth of coverage and the ability to improve upon the standard-of-care; the design, timing of initiation, progress and expected results of Vaxcyte’s clinical trials and regulatory plans; the demand for Vaxcyte’s vaccine candidates; and other statements that are not historical fact. The words “anticipate,” “believe,” “could,” “expect,” “intend,” “may,” “on track,” “potential,” “should,” “would” and similar expressions (as well as other words or expressions referencing future events, conditions or circumstances) convey uncertainty of future events or outcomes and are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These forward-looking statements are based on Vaxcyte’s current expectations and actual results and timing of events could differ materially from those anticipated in such forward-looking statements as a result of risks and uncertainties, including, without limitation, risks related to Vaxcyte’s product development programs, including development timelines, success and timing of chemistry, manufacturing and controls and related manufacturing activities, potential delays or inability to obtain and maintain required regulatory approvals for its vaccine candidates, and the risks and uncertainties inherent with preclinical and clinical development processes; the success, cost and timing of all development activities and clinical trials; and sufficiency of cash and other funding to support Vaxcyte’s development programs and other operating expenses. These and other risks are described more fully in Vaxcyte’s filings with the Securities and Exchange Commission (SEC), including its Quarterly Report on Form 10-Q filed with the SEC on November 4, 2025 or in other documents Vaxcyte subsequently files with or furnishes to the SEC. All forward-looking statements contained in this press release speak only as of the date on which they were made and are based on management’s assumptions and estimates as of such date, and readers should not rely upon the information in this press release as current or accurate after its publication date. Vaxcyte undertakes no duty or obligation to update any forward-looking statements contained in this release as a result of new information, future events or changes in its expectations. Readers should not rely upon the information in this press release as current or accurate after its publication date.

Contacts:

Patrick Ryan, Executive Director, Corporate Affairs
Vaxcyte, Inc.
415-606-5135
media@vaxcyte.com

Jeff Macdonald, Executive Director, Investor Relations
Vaxcyte, Inc.
917-371-0940
investors@vaxcyte.com

¹Pneumococcal-naïve is defined as having no known prior history of IPD, pneumococcal pneumonia, or receipt of any licensed or investigational pneumococcal vaccine.
²In U.S. children under five years of age: CDC 2023 Active Bacterial Core (ABC) Surveillance data. IPD cases with missing serotype data were excluded, non-typeable cases were included in the denominator.
³In U.S. children five years of age or under: Grant LR et al., FrontPediatr.2024;12:1383748. Serotype percentages reflect 2017–2021 data (Supplemental Table 1). 
⁴Lower bound of the 2-sided 95% confidence interval of the difference in the proportions of participants with a ≥4-fold increase from Day 1 to Month 1 is greater than 10%, and lower bound of the 2-sided 95% confidence interval of the OPA geometric mean ratio is greater than 2.0.
⁵Lower bound of the 2-sided 95% confidence interval of the OPA geometric mean ratio is greater than 1.0.

FAQ

What is the OPUS Phase 3 trial for VAX-31 (PCVX) and when did dosing start?

OPUS is a pivotal, noninferiority Phase 3 trial evaluating VAX-31 versus PCV21 and PCV20; first participants were dosed on Dec 8, 2025.

How many participants will the VAX-31 OPUS trial (PCVX) enroll and when are topline results expected?

The trial is expected to enroll approximately 4,000 participants with topline safety, tolerability and immunogenicity results anticipated in Q4 2026.

What coverage does VAX-31 claim for IPD and pneumococcal pneumonia in U.S. adults 50+ (PCVX)?

VAX-31 is designed to cover approximately 95% of IPD and 88% of pneumococcal pneumonia in U.S. adults aged 50+.

How much broader coverage does VAX-31 offer versus current standard vaccines (PCVX)?

The company reports potential incremental coverage of 14–34% for IPD and 19–31% for pneumonia compared with current standard-of-care vaccines.

What are the OPUS primary immunogenicity success thresholds in the VAX-31 (PCVX) trial?

Primary objectives include noninferiority if the lower bound of the two-sided 95% CI for OPA GMR exceeds 0.667, and superiority if the lower bound exceeds 2.0 for certain serotypes.

Will VAX-31 results support a Biologics License Application (BLA) for PCVX and what is the timing?

Topline OPUS data are intended to serve as a cornerstone for a planned BLA; additional Phase 3 studies are planned in 2026 with readouts in 2027 to support filing.