Pneumococcal polysaccharide conjugate vaccine

Pfizer on Wednesday detailed results supporting its decision to advance the investigational 25-valent pneumococcal conjugate vaccine candidate PF-07872412 into Phase III studies, including data showing stronger immune responses than the approved 20-variant shot Prevnar 20. The findings were presented at the International Society of Pneumonia & Pneumococcal Diseases (ISPPD) meeting.The results come from a Phase II study, which randomised healthy infants to receive PF-07872412 or Prevnar 20 at months 2, 4, 6 and 12–15. While Prevnar 20 is approved for the prevention of invasive disease caused by 20 Streptococcus pneumoniae strains, PF-07872412 seeks to build on this by adding protection against an additional five serotypes — 15A, 23A, 23B, 24F and 35B.In the trial, Pfizer said that PF-07872412 demonstrated "robust immunogenicity," including enhanced response against serotype 3, alongside expanded protection across the 25 serotypes. The company added that based on these immune responses, it is "confident" that the required non-inferiority thresholds will be achieved in further studies.Specifically, one month after the third dose, geometric mean titers for serotype 3 were 8.8-fold higher with PF-07872412 than with Prevnar 20 in the Phase II trial. Meanwhile, one month after dose four, geometric mean titers for serotype 3 were approximately 15-fold higher with the 25-valent vaccine than with Prevnar 20.Pfizer indicated that PF-07872412's safety profile was "consistent" with currently-approved pneumococcal vaccines, with the most common local reactions being redness, swelling or pain at the injection site."These…results reinforce our confidence in a next-generation vaccine," said Annaliesa Anderson, Pfizer's chief vaccines officer. "We are advancing our Phase III programme with the goal of delivering broader and more durable protection for children."The pivotal paediatric programme — which was initiated this month — is designed to investigate PF-07872412 versus Prevnar 20 in up to 2400 individuals. Pfizer hopes that if successful, the new vaccine will broaden protection to about 90% of disease-causing pneumococcal serotypes in US children.Prevnar 20 is currently approved in both infants and adults, with the vaccine, along with the older version Prevnar 13, generating combined sales of $6.5 billion last year. Pfizer said Wednesday that in an effort to maintain its current leadership in the adult market over the long term, it will move directly to a vaccine candidate covering 35 serotypes. The shot is expected to enter clinical development by the end of 2026.

Pfizer (NYSE: PFE) reported Phase II results for its 25-valent pneumococcal conjugate vaccine candidate PF-07872412 (25vPnC) in healthy infants. The immunogenicity data showed substantially higher serotype 3 responses compared with Prevnar 20 (pneumococcal 20-valent conjugate vaccine), supporting the company’s decision to initiate a pivotal Phase III pediatric program. The readout, presented at the International Society of Pneumonia and Pneumococcal Diseases meeting in Copenhagen, positions the Pfizer pneumococcal vaccine candidate as a potential successor to the current 20-valent standard of care. In the Phase II study NCT06524414, infants received a four-dose series of either 25vPnC or Prevnar 20 at months 2, 4, 6, and 12–15. Geometric mean titers for serotype 3 were 8.8-fold higher with 25vPnC than with Prevnar 20 one month after dose 3 (4.22 vs. 0.48), rising to approximately 15-fold higher one month after dose 4 (13.85 vs. 0.92), the company said. The safety and tolerability profile of 25vPnC was consistent with currently approved pneumococcal vaccines, with the most common local reactions being redness, swelling, and injection-site pain. No safety concerns were identified. The Phase II study is a randomized trial in healthy infants that enrolled participants beginning in July 2024, evaluating immunogenicity one month after dose 3 and one month after dose 4 across all 25 serotypes. The data presented reflect preliminary results from the broader study; full immunogenicity results across all serotypes were not disclosed in the press release, and the study remains ongoing. The company stated that immune responses observed for all 25vPnC serotypes from Phase II were strong compared with Prevnar 20, and that it is confident the required non-inferiority thresholds may be achieved in the Phase III program. The data remain preliminary and are based on interim findings from a study not yet fully reported. The 25vPnC vaccine candidate is a multivalent pneumococcal conjugate vaccine that elicits functional serotype-specific anti-capsular antibody responses against 25 Streptococcus pneumoniae serotypes, adding five serotypes — 15A, 23A, 23B, 24F, and 35B — to the 20 covered by Prevnar 20, alongside enhanced immunogenicity against serotype 3 through a next-generation conjugation technology. Prevnar 20, the current pediatric standard of care, met non-inferiority criteria for all 13 matched serotypes after dose 3 and for all 20 serotypes after doses 3 and 4 in its own Phase III pediatric program (NCT04382326). Merck’s Vaxneuvance (pneumococcal 15-valent conjugate vaccine), a 15-valent alternative, demonstrated non-inferiority to PCV13 for 13 shared serotypes and higher immune responses for serotypes 22F and 33F in Phase III infant development (NCT04031846). Cross-trial comparisons are limited by differences in study design, duration, and patient populations. This article was generated with AI assistance and reviewed and edited by the AllSci editorial team Explore more at AllSci News: https://allsci.com/news/ Your email address will not be published. Required fields are marked * Comment * Name * Email * Website Privacy Terms About Us Copyright © 2026. AllSci Corp. All rights reserved.