PREPARE Phase III trial of ResVax shows efficacy in respiratory syncytial virus

Novavax announced the presentation of new data from the company’s Prepare trial, a global Phase III clinical trial of ResVax, an aluminum adjuvanted respiratory syncytial virus (RSV) fusion (F) protein recombinant nanoparticle vaccine. The presentation included new observations based on the recently completed analyses of the 1-year safety data, including a 59.6% (95% CI 34.5, 71.7%) reduction in the incidence of serious adverse events (SAEs) diagnosed as pneumonia, with confirmation by chest x-ray, that extended through the first year of life. A similar efficacy of approximately 50% (95% CI 31.3, 62.7%) was found for all SAEs with a clinical diagnosis of pneumonia, also extending over a year.

When x-ray-confirmed pneumonia SAEs associated with detection of RSV were considered, efficacy was 72.9% (95% CI. 45.7, 86.5%) through 180 days of life, the last time point at which active detection of RSV was carried out. Geeta K. Swamy, M.D., Associate Professor of Obstetrics and Gynecology at Duke University made the presentation at the 2019 IDSOG Annual Meeting held in Big Sky, Montana.

Comment: Infants born to women in the vaccine group posted an RSV incidence rate of about 1.5% compared to the control group's rate of 2.4%. That improvement, of about 40%, was not enough to meet statistical level for declaring success. The improvement rates for some of the secondary endpoints, such as on RSV hospitalizations and cases with severe hypoxemia, were modestly better at 44% and 48% respectively.