SSRN Electronic Journal | 2021
Comparison of the Immunogenicity of BNT162b2 and CoronaVac COVID-19 Vaccines in Hong Kong: An Observational Cohort Study
Abstract
Background: COVID-19 vaccination programs are ongoing world-over using a wide array of vaccines. The performance of vaccines has been evaluated for immunogenicity and efficacy in separate clinical trials, but few head-to-head evaluations of vaccine responses have been carried out. \n \nMethods: An age-matched cohort that received 2 doses of either BNT162b2 (=49) or CoronaVac (n=49) were recruited from adults in the community in Hong Kong SAR, China. The humoral and cellular immune responses were examined to determine the levels of SARS-CoV-2 neutralizing and binding antibody in plasma and T cell reactivity in peripheral blood mononuclear cells (PBMC). \n \nFindings: At one month after second dose of vaccine, BNT162b2 vaccines elicited significantly higher 50% plaque reduction neutralization test (PRNT50), PRNT90, surrogate virus neutralization (sVNT), spike receptor binding (RBD), spike N terminal domain binding (NTD), spike S2 domain binding antibody levels compared to those vaccinated with CoronaVac. All 49 vaccinees in each group developed detectable PRNT 50 antibody. The geometric mean titers (GMT) PRNT50 in those vaccinated with BNT162b2 and CoronaVac vaccines was 251.6 and 69.45 respectively (p<0.0001). Forty-eight (98%) of 49 vaccinated with BNT162b2 and 44 (89.8%) of 49 vaccinated with CoronaVac achieved the 50% protection threshold for PRNT50. Allowing for a two-fold waning of antibody titers over time, 98% of those receiving BNT162b2 would still be protected but only 53.1% of CoronaVac recipients would remain protected. Age was negatively correlated with PRNT90 antibody titers among all vaccine recipients or either one of the vaccine subgroups separately. Both vaccines resulted in comparable levels of CD4 and CD8 T cell responses to spike protein at 1 month of post-vaccination. \n \nInterpretation: Vaccination with BNT162b2 induces significantly higher levels of SARS-CoV-2 specific binding and neutralizing antibody responses compared to CoronaVac and these differences are likely to result in differences in protection from infection. The two vaccines induce comparable CD4 and CD8 T cell responses. These findings are of relevance for decisions on the need for booster vaccines and for public health control of SARS-CoV-2. \n \nFunding Information: The Health and Medical Research Fund Commissioned Research on the Novel Coronavirus Disease (#COVID-1903003), Hong Kong SAR (see Acknowledgments for full list). \n \nDeclaration of Interests: We declare no competing interests. \n \nEthics Approval Statement: The study has been approved by the Joint Chinese University of Hong Kong-New Territories East Cluster Clinical Research Ethics Committee (Ref no: 2020.229) and all participants provided written consent.