Phase 1/2 Randomized Study of the Immunogenicity, Safety, and Tolerability of a Respiratory Syncytial Virus Prefusion F Vaccine in Adults With Concomitant Inactivated Influenza Vaccine

J Infect Dis. 2022 Jun 15;225(12):2056-2066. doi: 10.1093/infdis/jiab611.


Background: Respiratory syncytial virus (RSV) causes substantial morbidity and mortality in older adults and adults with comorbidities. An effective vaccine is needed. An investigational bivalent prefusion F vaccine (RSVpreF) was assessed in healthy adults.

Methods: This phase 1/2 study randomized adults 18-85 years old to receive placebo or 60, 120, or 240 µg RSVpreF (with or without aluminum hydroxide) alone or concomitantly with seasonal inactivated influenza vaccine (SIIV). Safety and immunogenicity were assessed.

Results: In older adults, reactogenicity events were predominantly mild or moderate among RSVpreF recipients; adverse events through 1 month postvaccination were similar across formulations. Coadministration with SIIV did not appear to affect safety among younger or older adults. All RSVpreF formulations with or without concomitant SIIV elicited robust RSV serum-neutralizing responses in adults aged 50-85 years 1 month postvaccination. Neutralizing titers 1 and 12 months postvaccination were 6.9-14.9 and 2.9-4.5 times, respectively, those before vaccination. SIIV immune responses trended lower when coadministered with RSVpreF.

Conclusions: RSVpreF formulations administered alone or with SIIV were well tolerated and highly immunogenic in older adults, supporting the potential for RSVpreF to protect older adults from RSV disease.

Clinical trials registration: NCT03529773.

Keywords: F protein; immunogenicity; older adults; respiratory syncytial virus; safety; vaccine.

Publication types

  • Clinical Trial, Phase I
  • Clinical Trial, Phase II
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Antibodies, Neutralizing
  • Antibodies, Viral
  • Humans
  • Immunogenicity, Vaccine
  • Influenza Vaccines* / administration & dosage
  • Influenza, Human / epidemiology
  • Middle Aged
  • Respiratory Syncytial Virus Infections / epidemiology
  • Respiratory Syncytial Virus Infections / prevention & control
  • Respiratory Syncytial Virus Vaccines* / adverse effects
  • Respiratory Syncytial Virus, Human
  • Vaccines, Inactivated / administration & dosage
  • Young Adult


  • Antibodies, Neutralizing
  • Antibodies, Viral
  • Influenza Vaccines
  • Respiratory Syncytial Virus Vaccines
  • Vaccines, Inactivated

Associated data