Transition of antibody titers after the SARS-CoV-2 mRNA vaccine in Japanese healthcare workers

Abstract

Since February 2021, health care workers in Japan have been preferentially vaccinated with a messenger RNA vaccine (BNT162b2/Pfizer) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). While many studies have confirmed that this vaccine is highly effective in reducing hospitalizations and deaths from coronavirus disease 2019 (COVID-19), antibody titers tend to decline at 3 months, leading to a risk of breakthrough infections. Thus, information is needed to support decision making regarding the third vaccination. In this study, we investigated transition of the anti-SARS-CoV-2 receptor-binding domain (RBD) IgG and neutralizing antibody titers of 41 vaccinated Japanese healthcare workers. Samples were collected seven times starting 1 week before vaccination until 6 months post-vaccination. Anti-SARS-CoV-2 RBD IgG levels peaked at 7 days after the booster, then declined over time and decreased to <10% at 6 months after the booster. Workers with low anti-SARS-CoV-2 RBD IgG levels also had low neutralizing antibody titers. These data support the active use of boosters for healthcare workers, especially for those with low anti-SARS-CoV-2 RBD IgG levels.

CD8+T-cell memory induced by successive SARS-CoV-2 mRNA vaccinations is characterized by clonal replacement

“…To analyze the kinetics of T cell clones following mRNA vaccination to SARS-CoV-2, we studied a cohort of 41 healthcare workers at Nara Medical University (Japan) who had received two doses of the Pfizer-BNT162b2 vaccine ( 15 ). Peripheral blood mononuclear cell (PBMC) samples were collected from the participants at four points: before the first dose (point 1: P1), seven days after the first dose (P2), seven days after the second dose (P3), and 28 days after the second dose (P4) (Fig.…”

“…As far as we know, this is the first report of longitudinal TCR repertoire data before and after the mRNA vaccination with 41 participants, enabling the global analysis of the kinetics of T-cell clones. Moreover, all participants reported no history of SARS-CoV-2 infection ( 15 ). Thus, our data represent the exclusive effect of mRNA vaccination on T-cell repertoire, although we can’t exclude that some participants may have been asymptomatically infected.…”

“…PBMCs were isolated from whole blood with BD vacutainer CPT tubes (BD), resuspended in CELLBANKER 1 (Takara), and stored at −80°C. The detailed study design was described in Kitabatake et al ( 15 ).…”