Pfizer RSV Vaccine Study  


A Phase 3 trial has been initiated as a randomized, double- or observer-blinded, placebo-controlled study to assess the efficacy and safety of a respiratory syncytial virus (RSV) prefusion F subunit vaccine in infants born to women who were vaccinated during pregnancy.


The urgent medical need for an effective RSV prophylaxis in infancy is substantial, given the millions of cases of RSV-related disease reported annually worldwide. Maternal immunization presents an appealing strategy for preventing infant RSV disease.

Preclinical studies in animals and interim data from a Phase 1/2 trial involving healthy nonpregnant adults have demonstrated the acceptable tolerability and safety of RSVpreF. Notably, a robust immune response has been observed in the trial population one month post-vaccination. The combined RSV A and B serum neutralization geometric mean titers (GMTs) achieved with RSVpreF are 12 to 20 times higher than those attained with a concentration of 100 μg/ml of palivizumab, a monoclonal antibody known to offer near-complete protection against severe RSV disease in high-risk infants.

Currently, RSVpreF is undergoing evaluation in healthy pregnant women aged 11 to 49 years in Study C3671003: A Phase 2b, Randomized, Placebo-Controlled, Observer-Blinded Trial to Evaluate the Safety, Tolerability, and Immunogenicity of a Respiratory Syncytial Virus (RSV) Vaccine in Pregnant Women and Their Infants ( identifier: NCT 04032093). This Phase 3 trial, employing a randomized, double- or observer-blinded, placebo-controlled design, aims to assess the efficacy and safety of maternal immunization with RSVpreF in preventing medically attended RSV-associated lower respiratory tract infections (LRTI) in infants.


  • Dr Elizea Horne (Principal Investigator)
  • Dr Faeezah Patel (Sub-Investigator)
  • Dr Mrinmayee Dhar (Sub-Investigator)
  • Dr Muneerah Khan (Sub-Investigator)
  • Dr Jeanne Coetzee (Sub-Investigator)
  • Tiffany Seef (Clinical Associate)
  • Othusitse Segalo (Clinical Associate)

Latest Update

March 2024

For more about Pfizer RSV Vaccine Study please email

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