Antibody responses after a double dose of SARS-CoV-2 mRNA vaccine

ABSTRACT

Background and Aim: Vaccination against SARS-CoV-2 started in Italy in January 2021. First, healthcare personnel were vaccinated. Immunization of subjects should lead to a reduction in the clinical manifestations of the disease. Aim of the study was to evaluate the antibody response after the administration of two doses of the BNT162b2 SARS-CoV-2 mRNA vaccine. Materials and Methods: We determined antibody levels at baseline (before second dose of vaccine) and 3 weeks after the second dose of the BNT162b2 SARS-CoV-2 mRNA vaccine in 92 (middle age 44±12 ) health care workers (35 male 38%, and 57 female). Written informed consent was obtained for all study participants. Results: Antibody responses was of 452 U/mL±2744 (median 36, interquartile range 9-99) vs 3154±4389 (median 1957, interquartile range 1242-3238) p<0.001 (average increase of 2702±2554). Excluding 3 cases with baseline value>1000 the response was 63±92 (median 35, interquartile range 8-78) vs 2693±2410 (median 1912, interquartile range 1241-3136) p<0.001 (average increase of 2630±2369). According to multivariate regression analysis: baseline is inversely associated with age (p <0.001) but not with sex (p=0.393);post sampling is inversely associated with age (p=0.003) but not with sex (p=0.653). Conclusions: Our data demonstrate that the antibody response after the administration of two doses of the BNT162b2 SARS-CoV-2 mRNA vaccine was obtained in 100% of the subjects studied. In particular, there is a relationship with age younger subjects show a more robust response. Gender does not influence extent of response.