Conference Poster Year : 2024

P-2055. Modelling the Relative Vaccine Effectiveness of ARCT-154 versus BNT162b2 in Younger and Older Adults

Abstract

Background: While vaccines have proved a key tool in protection from COVID-19, the duration of immunity induced by first-generation mRNA vaccines is limited. Self-amplifying mRNA (SA-mRNA) vaccines have clinically shown to both elicit higher antibody responses and increase the duration of response. In this analysis, we evaluate the relative vaccine effectiveness (rVE) over time of a COVID-19 SA-mRNA vaccine (ARCT-154) versus BNT162b2 against the original Wuhan-Hu-1 and Omicron BA.4/BA.5 strains in adults stratified by age group (< 60 years and ≥60 years), using a correlate of protection derived from immunogenicity data. Methods: We used geometric mean titer data collected on Days 29, 91, and 181 post-vaccination from a phase 3 clinical trial comparing the immune response of ARCT-154 and BNT162b2 against Wuhan-Hu-1 and Omicron BA.4/5 in healthy 18–77-year-olds (Japan Registry for Clinical Trials identifier: jRCT2071220080) to estimate a correlate of protection against symptomatic and severe COVID-19. rVE of ARCT-154 versus BNT162b2 was then evaluated for each time point against both endpoints in individuals < 60 years and ≥60 years of age. Results: rVE against symptomatic infection and severe illness increased over time against both Wuhan-Hu-1 and Omicron BA.4/BA.5. In adults < 60 years, rVE against symptomatic infection ranged from 2.57% on Day 29 to 9.19% on Day 181 against Wuhan-Hu-1 and from 4.24% to 26.83% against Omicron BA.4/5. In adults ≥60 years, rVE ranged from 2.77% to 10.99% and 4.58% to 48.02% against the two strains, respectively. rVE against severe illness ranged from 0.30% to 4.65% against Wuhan-Hu-1 and 0.63% to 15.84% against Omicron BA.4/5 in adults < 60 years and from 0.34% to 5.61% and 0.74% to 27.96%, respectively, in adults ≥60 years. Conclusion: ARCT-154 showed longer-lasting protection than BNT162b2 against symptomatic and severe COVID-19, with greatest benefits in adults ≥60 years of age against Omicron BA.4/BA.5.

Dates and versions

hal-04930465 , version 1 (05-02-2025)

Identifiers

Cite

Van Nguyen, Pascal Crepey, Jean Marie Pivette, Ettan Settembre, Sankarasubramanian Rajaran, et al.. P-2055. Modelling the Relative Vaccine Effectiveness of ARCT-154 versus BNT162b2 in Younger and Older Adults. IDWeek 2024, Oct 2024, Los Angeles, California, United States. Open Forum Infectious Diseases, Volume 12, Issue Supplement_1, February 2025, 12 (Supplement_1), pp.S1219, 2025, ⟨10.1093/ofid/ofae631.2211⟩. ⟨hal-04930465⟩
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