Difference in the Dynamics of Antibody Titer between COVID-19 Vaccination and SARS-CoV-2 Infection in Healthcare Workers –A Case Study Based on Long-Term and Dense Measurement of Antibody Titer

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is prevalent worldwide, and effective and safe vaccines against the virus have been developed. Although trends in antibody titers after vaccination and/or SARS-CoV-2 infection have been reported, the length and frequency of the measurements are limited. This case report describes the long-term and detailed trends in the anti-SARS-CoV-2 S protein receptor-binding domain (S-RBD), repeatedly measured after vaccination and/or infection in three healthcare workers. All healthcare workers received 30 μg of the mRNA vaccine, BNT162b2, during all vaccinations. The peak value of the SARS-CoV-2 S-RBD titer reached at 1–2 week(s) after vaccination, decreased by half within 8 weeks after the vaccination, and the peak values of the antibody titer increased with repeated vaccinations. In contrast, after SARS-CoV-2 infection, the peak value of the antibody titer reached at 4–8 weeks after the infection, but the elevated antibody titer remained up to 16 and 40 weeks after the peak. The present case report shows long-term and detailed trends of SARS-CoV-2 S-RBD titer, with different patterns after vaccination and/or SARS-CoV-2 infection.