Researchers in China have published interim results from ongoing randomised, double-blind, placebo-controlled, phase 1 and 2 trials assessing an inactivated COVID-19 vaccine. The interim analysis was conducted on June 16 and updated on July 27.
In the phase 2 trial, 224 (aged 18-59 years) healthy participants were randomised to 5 μg/dose of the vaccine in two schedules; vaccine injections on days 0 and 14 (n=84) vs aluminium hydroxide (alum) only (n=28), and days 0 and 21 (n=84) vs alum only (n=28).
Adverse reactions (ARs) occurred in five (6.0%) and four (14.3%) participants in the first schedule group, and 16 (19.0%) and five (17.9%) receiving the second schedule group.
The most common ARs were injection site pain and fever, which were mild and self-limiting. No serious ARs were noted.
The geometric mean titres of neutralising antibodies were 121 (95% CI 95-154) and 247 (95% CI 176-345) at day 14 after injections on days 0 and 14 and on days 0 and 21, respectively. There were no detectable antibody responses in alum-only groups.
The findings demonstrate immunogenicity and suggest the inactivated vaccine is associated with a low rate of ARs.
. Phase 3 trials will be needed to confirm these findings.