COMPARATIVE IMMUNOGENICITY OF BNT162b2 mRNA VACCINE WITH NATURAL COVID-19 INFECTION

ABSTRACT The mRNA vaccine BNT162b2 has proven highly effective and currently many millions are being vaccinated. There are limited and conflicting data from immunogenicity studies on the effects of age, gender, vaccination side effects (VSE), risk factors for severe COVID-19 (RFS-COV), obesity (BMI) and previous SARS-CoV-2 (Pr-CoV) Moreover, immunogenicity data from COVID-19 patients comparing various disease categories of natural infection i.e. asymptomatic vs mild vs moderate vs severe infection are sparse, and include limited number of individuals. This study included 871 vaccinated health care workers (HCW) and 181 patients with natural infection. Immunogenicity was assessed by a quantative assay measuring anti-SARS-CoV-2 against the RBD domain of the spike protein (anti-RBD) and anti-SARS-CoV-2 against nucleocapsid protein (anti-N). Samples were collected 1-2 weeks after completion of the 2nd dose in the vaccinated HCWs and 15-59 days post symptoms onset in patients with natural infection. The concentration of anti-RBD in vaccinated individuals after multivariable analysis was significantly associated with age, gender, VSE and Pr-CoV. Specifically, anti-RBD median levels (95% CI) were lower by 2,466 (651-5,583), 6,228 (3,254-9,203) and 7,651 (4,479-10,823) AU/ml in 35-44, 45-54, 55-70 yrs respectively, compared with 18-34 yrs group. In females, median levels of anti-RBD were higher by 2,823 (859-4,787) compared with males, in individuals with VSE were higher by 5,024 (3,122-6,926) compared with no VSE, and in HCWs with Pr-CoV were higher by 9,971 (5,158-14,783) AU/ml compared with HCWs without Pr-CoV. Among individuals with natural infection, the median anti-RBD levels were 14.8 times higher in patients with critical COVID-19 infection compared with non-hospitalized individuals. The ratio of anti-RBD in vaccinated individuals versus those with natural infection varied from 1.0 up to 19.4 according to the clinical subgroup of natural infection. This study proves the high immunogenicity of BNT162b2 vaccine although its sustainability remains to be seen. The use of comparative data from natural infection serological panels, expressing the clinical heterogeneity of natural infection may facilitate early decisions for vaccine evaluation in clinical trials.