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Published on: December 10, 2013
Live-Attenuated Intranasal RSV Vaccine in Infants and Toddlers
Olubukola T Idoko1, Sergio L Vargas2, Agustin Bueso3
1Sanofi, Marcy l'Étoile, France.
Insights
The investigational live-attenuated intranasal respiratory syncytial virus (RSV) vaccine, RSVt, showed promising safety and immunogenicity in infants and toddlers. This RSV vaccine candidate warrants further investigation for infant and toddler protection against RSV infection.
Area of Science:
- Virology and Vaccinology
- Pediatric Infectious Diseases
- Clinical Trial Research
Background:
- Respiratory Syncytial Virus (RSV) poses a significant health threat to infants and toddlers.
- RSV/ΔNS2/Δ1313/I1314L (RSVt) is an intranasal live-attenuated vaccine candidate developed by Sanofi for RSV prevention.
Purpose of the Study:
- To evaluate the safety and immunogenicity of the candidate live-attenuated intranasal RSV vaccine (RSVt) in infants and toddlers.
- To compare low-dose (LD) and high-dose (HD) RSVt against a placebo in a Phase I/II clinical trial.
Main Methods:
- A Phase I/II randomized clinical trial enrolled 180 participants aged 6-18 months across US, Chile, and Honduras.
- Participants in cohort 4 received two vaccinations (days 0 and 56) of LD RSVt, HD RSVt, or placebo.
- Safety was assessed by adverse events within 30 minutes post-vaccination and solicited reactions within 28 days; immunogenicity was measured by RSV A serum neutralizing antibody titers.
Main Results:
- No unsolicited systemic adverse events were observed within 30 minutes post-vaccination in RSVt groups.
- Solicited reactions were generally comparable between RSVt groups and the placebo group.
- RSV-naive participants in both LD and HD RSVt groups demonstrated significantly higher neutralizing antibody titers compared to the placebo group after both vaccinations.
Conclusions:
- The RSVt vaccine candidate exhibited a promising safety profile in infants and toddlers.
- Both low and high doses of RSVt demonstrated robust immunogenicity, suggesting potential efficacy in preventing RSV.
- Further studies are warranted to confirm the efficacy and long-term safety of RSVt.
Background:
RSV/ΔNS2/Δ1313/I1314L (RSVt) (Sanofi) is a candidate live-attenuated intranasal respiratory syncytial virus (RSV) vaccine for infants and toddlers.
Methods:
This phase I/II randomized clinical trial, conducted at sites in the United States (N=22), Chile (N=2), and Honduras (N=2), enrolled participants 6-18 months of age in four cohorts. In cohort 4, the primary cohort reported in this article, participants were randomly assigned to receive vaccinations on days 0 and 56 of either low-dose (LD) RSVt, high-dose (HD) RSVt, or placebo. Primary safety end points included: unsolicited systemic adverse events 30 minutes post vaccination, and solicited site and systemic reactions 28 days post vaccination. The primary immunogenicity end points were the geometric mean titers of RSV A serum neutralizing antibody after vaccinations 1 (day 56) and 2 (day 84) among RSV-naive participants at baseline.
Results:
Among 180 participants (LD, N=61; HD, N=58; placebo, N=61), 115 were RSV-naive at baseline (LD, N=45; HD, N=32; placebo, N=38). No unsolicited systemic adverse events occurred within 30 minutes post vaccination in the LD or HD groups. Solicited site reactions were reported by 83.1%, 74.5%, and 68.9% of participants post vaccination 1, and 75.6%, 77.8%, and 55.6% post vaccination 2, in the LD, HD, and placebo groups, respectively. Solicited systemic reactions were reported by 79.7%, 73.2%, and 77.0% of participants post vaccination 1, and 66.7%, 66.7%, and 48.1% post vaccination 2, in the LD, HD, and placebo groups, respectively. Neutralizing antibody titers among RSV-naive participants were 83.7 (95% confidence interval (CI), 49.5 to 142.0), 79.4 (95% CI, 47.2 to 134.0), and 20.6 (95% CI, 16.4 to 25.9) post vaccination 1, and 142.0 (95% CI, 86.4 to 232.2), 107.0 (95% CI, 70.0 to 163.0), and 26.3 (95% CI, 18.8 to 37.0) post vaccination 2, in the LD, HD, and placebo groups, respectively.
Conclusions:
The RSVt vaccine demonstrated promising immunogenicity profiles at both LD and HD strengths among infants and toddlers, without identified safety concerns. (Funded by Sanofi; ClinicalTrials.gov number, NCT04491877).
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