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Updated: Jul 7, 2026
An In vitro Model to Study Immune Responses of Human Peripheral Blood Mononuclear Cells to Human Respiratory Syncytial Virus Infection
Published on: December 10, 2013
A Phase 1/2a Study Evaluating Safety and Immunogenicity of Ad26.RSV.preF in RSV-seronegative Toddlers Aged 12-24
Joanne M Langley1, Terry M Nolan2,3, Mika Rämet4
1Canadian Center for Vaccinology, Dalhousie University, IWK and Nova Scotia Health, Halifax, Nova Scotia, Canada.
Insights
The Ad26.RSV.preF vaccine candidate demonstrated good tolerability and immunogenicity in RSV-seronegative toddlers. This study assessed its safety and immune response in young children, showing promising results for future respiratory syncytial virus prevention.
Area of Science:
- Pediatric infectious diseases
- Vaccine development and immunology
- Viral respiratory infections
Background:
- Respiratory syncytial virus (RSV) poses a significant health risk to young children.
- Previous studies indicated the Ad26.RSV.preF vaccine candidate's immunogenicity and safety in RSV-seropositive children.
- This study specifically evaluated the vaccine in RSV-seronegative toddlers.
Purpose of the Study:
- To assess the safety and immunogenicity of the Ad26.RSV.preF vaccine candidate in RSV-seronegative toddlers.
- To monitor for adverse events and RSV infection rates following vaccination.
- To evaluate the vaccine's ability to elicit neutralizing antibodies against RSV.
Main Methods:
- A randomized, observer-blinded, placebo-controlled phase 1/2a study was conducted in RSV-seronegative toddlers (12-24 months).
- Participants received Ad26.RSV.preF or placebo on three occasions, with safety endpoints including solicited and unsolicited adverse events.
- Immunogenicity was assessed by measuring RSV-A2 neutralizing antibodies, and RSV preF and postF binding antibodies.
Main Results:
- The Ad26.RSV.preF vaccine was generally well-tolerated, with solicited adverse events being mostly mild to moderate.
- No serious adverse events were attributed to the vaccine.
- Vaccine recipients showed significant increases in RSV-specific antibodies, indicating a robust immune response.
Conclusions:
- The Ad26.RSV.preF vaccine candidate is safe and immunogenic in RSV-seronegative toddlers.
- These findings support the further development of Ad26.RSV.preF for pediatric RSV prevention.
- The vaccine candidate shows potential for protecting young children against RSV illness.
Background:
Respiratory syncytial virus (RSV) causes serious illness in children. The Ad26.RSV.preF vaccine candidate was immunogenic with acceptable safety in a phase 1/2a study of RSV-seropositive children. Here, we assessed its safety and immunogenicity in RSV-seronegative children.
Methods:
In this randomized, observer-blinded, placebo-controlled, phase 1/2a study (NCT03606512; https://www.clinicaltrials.gov/ct2/show/NCT03606512), RSV-seronegative toddlers aged 12-24 months received Ad26.RSV.preF (2.5 × 1010 viral particles) or placebo on days 1, 29, and 57 (a meningococcal vaccine [Nimenrix] could substitute for day 57 placebo). Primary endpoints were solicited local and systemic adverse events (AEs; 7 days after each vaccination), unsolicited AEs (28 days postvaccination), and serious AEs (first vaccination until study end). Participants were monitored for RSV-respiratory tract infection to assess infection rates and for severe RSV-lower respiratory tract infection as an indication of enhanced disease. RSV-A2 neutralizing, RSV (A and B) preF binding, and RSV postF immunoglobulin G-binding antibodies were evaluated on days 1 (predose), 8, and 85, and after RSV season 1.
Results:
Thirty-eight participants were enrolled and vaccinated (Ad26.RSV.preF, n = 20; placebo, placebo/Nimenrix, n = 18). Solicited AEs were more common following Ad26.RSV.preF than placebo; most were mild/moderate. No vaccine-related serious AEs were reported. Five of 19 participants receiving Ad26.RSV.preF and 2/18 receiving placebo or placebo/Nimenrix had confirmed RSV-respiratory tract infection or RSV-associated otitis media; none were considered severe. At the final season 1 study visit, most Ad26.RSV.preF recipients had ≥2-fold increases from baseline in RSV-A2 neutralizing, RSV A and B preF binding, and RSV postF antibodies.
Conclusions:
Ad26.RSV.preF was well tolerated and immunogenic in RSV-seronegative toddlers.
