Detection of neutralizing antibodies of a recombinant adenovirus type-5 vectored COVID-19 vaccine in healthy adults in China

We conducted a descriptive analysis of the specific IgM, IgG, and Nabs test results of participants with the rAd5 vectored COVID-19 vaccine to provide reference information for the vaccine's protective efficacy.The levels of specific IgM, IgG, and Nabs antibodies in 111 participants vaccinated with the rAd5 vectored COVID-19 vaccine were measured by chemiluminescence results were compared and analyzed.We found that IgG and NAbs concentrations in all participants were inversely correlated with age, and significant differences were found between age groups.102 (91.89%) and 95 (85.59%) participants were positive for 2019-nCoV IgG and NAbs, respectively.The IgG concentrations of participants younger than 40 years old were generally higher than that of participants older than 40 years old (P= 0.025).Similar results were found at the NAbs concentrations (P= 0.05).Our findings demonstrate that the NAbs of the rAd5 vectored COVID-19 vaccine was more than 85% in the Chinese, which provided certain reference information for the vaccine's protective efficacy.