npj Vaccines (Nov 2024)

A randomized trial comparing safety, immunogenicity and efficacy of self-amplifying mRNA and adenovirus-vector COVID-19 vaccines

  • Nhan Thi Ho,
  • Steve G. Hughes,
  • Rose Sekulovich,
  • Van Thanh Ta,
  • Thuong Vu Nguyen,
  • Anh Thi Van Pham,
  • Quang Chan Luong,
  • Ly Thi Le Tran,
  • Anh Thi Van Luu,
  • Anh Ngoc Nguyen,
  • Ha Thai Pham,
  • Van Thu Nguyen,
  • Dina Berdieva,
  • Roberto Bugarini,
  • Xuexuan Liu,
  • Carole Verhoeven,
  • Igor Smolenov,
  • Xuan-Hung Nguyen

DOI
https://doi.org/10.1038/s41541-024-01017-5
Journal volume & issue
Vol. 9, no. 1
pp. 1 – 10

Abstract

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Abstract This phase 3 trial compared safety, tolerability, immunogenicity and efficacy of the self-amplifying mRNA COVID-19 vaccine, ARCT-154, with ChAdOx1-S adenovirus-vector vaccine. In four centers in Vietnam adult participants aged 18‒85 years were randomly assigned to receive two doses, 28 days apart, of either ARCT-154 (n = 1186) or ChAdOx1-S (n = 1180). Both vaccines were well tolerated with similar safety and reactogenicity profiles consisting of mainly mild-to-moderate solicited adverse events and few related serious adverse events. Higher neutralizing antibody responses persisting to one-year post-vaccination after ARCT-154 compared with ChAdOx1-S were associated with a generally higher efficacy against COVID-19. In an exploratory analysis relative vaccine efficacy of ARCT-154 vs. ChAdOx1-S against any COVID-19 from Day 36 to Day 394 was 19.8% (95% CI: 4.0–33.0). Self-amplifying mRNA vaccine offers potential immunological advantages in terms of immunogenicity and efficacy over adenovirus-vector vaccine without compromising safety.