Longitudinal dynamics of SARS-CoV-2 anti–receptor binding domain IgG antibodies in a wide population of health care workers after BNT162b2 vaccination

• DOI: 10.1016/j.ijid.2022.05.061
• Publication Date: 2022-05-31T15:58:57Z
• Authors: Licia Bordi; Giuseppe Sberna; Cesira Natalina P...; Rosario Andrea Co...; Anna Miani; Paola Grammatico; Bruno Mariani; Gabriella Parisi
• Keywords: Male; Health care workers; SARS-CoV-2; Health Personnel; Vaccination; COVID-19; Viral Vaccines; Infectious and parasitic diseases; RC109-216; Antibodies, Viral; Article; 3. Good health; 03 medical and health sciences; 0302 clinical medicine; Immunoglobulin G; Anti-RBD IgG; Humans; BNT162b2; Female; Longitudinal Studies; anti-rbd igg; bnt162b2; health care workers; humoral response; sars-cov-2; Humoral Response; BNT162 Vaccine

With the availability of vaccines, commercial assays detecting anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies evolved toward quantitative assays directed to the spike glycoprotein or its receptor-binding domain (RBD). The objective was to perform a large-scale, longitudinal study involving health care workers (HCWs), with the aim of establishing the kinetics of immune response throughout the 9-month period after receipt of the second dose of the BNT162b2 vaccine.Quantitative determination of immunoglobulin (Ig) G antibodies against the RBD of the S1 subunit of the spike protein of SARS-CoV-2 on the Alinity systems.The highest levels of anti-RBD IgG were measured after 1 month from full vaccination (median: 1432 binding antibody units/ml [BAU/ml]); subsequently, a steep decrease (7.4-fold decrease) in IgG levels was observed at 6 months (median: 194.3 BAU/ml), with a further 2.5-fold decrease at 9 months (median: 79.3 BAU/ml). Furthermore, the same data, when analyzed for sex, showed significant differences between male and female participants at both 1 and 9 months from vaccination, but not at 6 months.Our results confirm the tendency of anti-RBD antibodies to decrease over time, also when extending the analysis up to 9 months, and highlight a better ability of the female sex to produce antibodies 1 month and 9 months after vaccination. Overall, these data, obtained in a wide population of HCWs, support the importance of having increased the vaccine doses.