July 24, 2020

Immunogenicity and Safety of a Recombinant Adenovirus Type-5-Vectored COVID-19 Vaccine in Healthy Adults Aged 18 Years or Older: A Randomised, Double-Blind, Placebo-Controlled, Phase 2 Trial

Category: Article Summary

Topic: Vaccines and Immunity

• Zhu et al. report findings from a phase 2 randomized, double-blind, placebo-controlled single-center (Wuhan) trial of an Ad5-vecctored COVID-19 vaccine. A total of 508 participants were randomly assigned to treatment (n=253 low dose, n=129 medium dose) or placebo (n=126; vaccine excipients with no viral particles). Both treatment groups had high seroconversion rates by 28 days (96% in the low dose group and 97% in the high dose group) and demonstrated significant neutralizing antibody responses, as well as significant T-cell responses. Adverse reactions were reported in 72% and 74% of the low- and high-dose treatment arms, versus 9% of the placebo arm, all of which were self-limiting and resolved within 72-96 hours without medication. No serious adverse reactions were documented within 28 days.  

Zhu et al. (July 2020). Immunogenicity and Safety of a Recombinant Adenovirus Type-5-Vectored COVID-19 Vaccine in Healthy Adults Aged 18 Years or Older: A Randomised, Double-Blind, Placebo-Controlled, Phase 2 Trial. The Lancet. https://doi.org/10.1016/S0140-6736(20)31605-6