Novavax’s respiratory syncytial virus failed to meet its Phase III trial endpoints, and did not demonstrate efficacy compared to placebo. The trial of the RSV F Vaccine enrolled 11,856 adults, 60 years of age and older, at 60 sites in the U.S.

The trial did not demonstrate prevention of moderate-severe RSV-associated lower respiratory tract disease, nor did it meet its secondary objective of reducing the incidence of all symptomatic respiratory disease due to RSV.

The attack rate for the primary objective was approximately 25 percent of that observed in a previous Phase II trial, according to the company. Novavax expects to have preliminary immunogenicity data in the coming weeks.