Pfizer Pneumococcal Vaccine Elicits Immune Response Across 25 Serotypes

Pfizer announced the advancement of its 25-valent pneumococcal conjugate vaccine candidate, PF-07872412, into pivotal phase 3 clinical trials. This decision follows positive phase 2 data demonstrating that the investigational vaccine is well-tolerated and elicits a robust immune response across all 25 included serotypes in infants.¹

“For more than 25 years, our vaccines have helped protect children from pneumococcal disease yet significant disease burden remains,” Annaliesa Anderson, PhD, senior vice president and chief vaccines officer at Pfizer, said in a news release.¹

For pharmacists, who serve as vital immunizers and educators within the health care system, these developments signal a potential shift in the standard of care for preventing a disease that remains a leading cause of serious illness in children.²

About the Trial Results

Technological innovation in vaccine design is at the heart of this new 25-valent candidate, which builds upon the foundation of the 20 serotypes in Prevnar 20. By adding 5 additional serotypes—15A, 23A, 23B, 24F, and 35B—this next-generation vaccine is expected to cover up to 90% of the disease-causing serotypes currently circulating in the pediatric population.¹

The phase 2 study compared the 25-valent candidate to the currently licensed 20-valent vaccine, Prevnar 20, administered in a 4-dose series at 2, 4, 6, and 12 to 15 months of age. Findings presented at the International Society of Pneumonia and Pneumococcal Diseases highlighted the vaccine's enhanced performance against serotype 3. Specifically, the 25-valent candidate produced serotype 3 immunogenicity responses that were approximately nine to 15 times higher than those seen with Prevnar 20 after the third and fourth doses. Serotype 3 remains a persistent driver of invasive disease and complicated pneumonia in children despite the success of previous vaccination programs.

Common reactions reported in the studies include redness, swelling, or pain at the injection site, which are similar to those seen with existing standard-of-care options.

The transition to phase 3 for the pediatric 25-valent vaccine involves a large-scale study of approximately 2400 healthy children to further confirm its safety and immunogenicity. This trial will continue to utilize the established 4-dose schedule, providing the durable protection necessary to combat the remaining disease burden.

“These phase 2 results reinforce our confidence in a next-generation vaccine designed to expand protection across serotypes while improving responses to key residual disease drivers such as serotype 3. We are advancing our phase 3 program with the goal of delivering broader and more durable protection for children,” Anderson said.¹

The Role of the Pharmacist

The role of the pharmacist in managing pneumococcal infection is increasingly centered on proactive identification and patient education. Although pneumococcal disease can range from mild ear infections to life-threatening meningitis and blood infections, it results in approximately 1500 serious cases annually among US children under 5 years of age.^2,3

Pharmacists are uniquely positioned to identify the estimated 6.8 million children and adolescents with chronic health conditions—such as asthma, diabetes, or sickle cell disease—that place them at higher risk for these complications. By maintaining an active role in the catch-up schedule for children under 5 years who have not completed their series, pharmacists ensure that the most vulnerable populations receive the best possible protection.³

Beyond the pediatric program, the broader landscape of pneumococcal prevention is also evolving for adults. Pfizer indicated that it is advancing an adult program for a fifth-generation 35-valent vaccine candidate, which is expected to enter clinical development by the end of 2026. This candidate also aims to utilize proprietary technology to improve the immune response for critical serotypes like serotype 3 in the adult market. As these programs progress, the pharmacist’s expertise in navigating the complexities of vaccine schedules and emerging clinical data will remain essential for public health.^1,3

READ MORE: Pneumococcal Resource Center

Are you ready to elevate your pharmacy practice? Sign up today for our free Drug Topics newsletter and get the latest drug information, industry trends, and patient care tips straight to your inbox.

REFERENCES

1. Pfizer advances pivotal pediatric pneumococcal vaccine program following strong positive phase 2 results. News release. Pfizer. May 20, 3036. Accessed May 20, 2026. https://www.pfizer.com/news/press-release/press-release-detail/pfizer-advances-pivotal-pediatric-pneumococcal-vaccine

2. National Foundation for Infectious Diseases. Pneumococcal Disease and Children. November 2025. Accessed May 20, 2026. https://www.nfid.org/infectious-diseases/pneumococcal-disease-and-children/

3. Nationwide Children’s. Pneumococcal Infection in Children. Updated February 1, 2025. Accessed May 20, 2026. https://www.nationwidechildrens.org/conditions/health-library/pneumococcal-infection-in-children