Pfizer RSV Vaccine Study

A phase 3, randomized, double-or observer-blinded, placebo-controlled trial to evaluate the efficacy and safety of a respiratory syncytial virus (RSV) prefusion f subunit vaccine in infants born to women vaccinated during pregnancy


There is a large unmet medical need that could be addressed by an effective RSV prophylaxis in infancy. Given the global burden of disease in millions of cases each year, maternal immunization offers an attractive strategy for infant disease prevention. Both preclinical studies in animals and interim data from a Phase 1/2 study in healthy nonpregnant adults have demonstrated acceptable tolerability and safety of RSVpreF. A robust immune response has also been observed in population of the aforementioned trial at I month after vaccination. The combined RSV A and B serum neutralization geometric mean titers (GMTs) have been shown to be 12 to 20 times higher than those with 100 ug/ml of palivizumab, the concentration of monoclonal antibody that is known to provide near to complete protection of high risk infants from severe RSV disease. RSVpreF is currently under assessment in healthy pregnant women 18 through 49 years of age (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 18 Through 49 Years of Age and Their Infants; identifier: NCT 04032093). This randomized, double-or observer-blinded, placebo-controlled Phase 3 study is designed to evaluate the efficacy and safety of maternal immunization with RSVpreF against medically attended RSV-associated LRTI in infants.

Primary Efficacy Objectives in Infant Participants

To evaluate the efficacy of RSVpreF in reducing the incidence of MA-LRTI due to RSV and severe MA-LRTI due to RSV

Primary Safety Objectives- Infant Participants

To describe the safety of RSVpreF

Study Design

Phase 3 multicentre, randomised, double or observer-blinded placebo-controlled study

Study Population

Healthy women between 18 and 49 years of age who are between 24/07- and 36/07-weeks gestation on the day of planned vaccination, with an uncomplicated, singleton pregnancy, who are at no known increased risk for complications


  • Dr Masebole Masenya, Principal Investigator
  • Prof Lee Fairlie, Sub Investigator
  • Dr Elizea Horne, Sub Investigator
  • Dr Faeezah Patel, Sub Investigator


  • Pfizer

Latest Update:

23 August 2021

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