A Randomized, Blinded, Controlled, Dose-Ranging Study of a Respiratory Syncytial Virus Recombinant Fusion (F) Nanoparticle Vaccine in Healthy Women of Childbearing Age

Background. Respiratory syncytial virus (RSV) is a leading cause of infant morbidity and mortality. A recombinant RSV fusion protein nanoparticle vaccine (RSV F vaccine) candidate for maternal immunization was tested for safety and immunogenicity in women of childbearing age. Methods.Three hundred thirty women (18-35 years) were randomized to receive 1 or 2 doses of RSV F vaccine (60 or 90 A mu g) with or without aluminum phosphate adjuvant, or placebo at days 0 and 28. Safety was evaluated over 180 days; immunogenicity and RSV infection rates were evaluated over 112 days. Results.All vaccine formulations were well tolerated, without vaccine-related serious adverse events. Anti-F immunoglobulin G antibodies rose 6.5-15.6-fold, with significantly higher levels in 2-dose, adjuvanted regimens at day 56. Palivizumab-competitive antibody levels were undetectable at day 0 but increased up to 325 A mu g/mL at day 56. A 2.7- and 3.5-fold rise in RSV/A and RSV/B microneutralization antibodies were noted at day 56. Between days 56 and 112, 21% (12/56) of placebo recipients and 11% of vaccinees (26/244) showed evidence of a recent RSV infection (P = .04). Conclusions.The vaccine appeared safe, immunogenic, and reduced RSV infections. Further development as a vaccine for use in maternal immunization is warranted. Clinical Trials Registration.NCT01704365.