Abstract
BackgroundThis study aimed at monitoring the kinetics of serum total anti-SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) antibodies in a cohort of healthcare workers after voluntary vaccination with Pfizer-BioNTech coronavirus disease 2019 (COVID-19) mRNA-based vaccine.MethodsThe study population consisted of 787 healthcare workers (mean age 44±12 years; 66% females), who received two 30 mg doses of Pfizer-BioNTech COVID-19 vaccine, 3 weeks apart. Venous blood was drawn before the first vaccine dose, immediately before the second vaccine dose, and then at 1, 3 and 6 months after the second vaccine dose. Serological testing employed the total antiSARS-CoV-2 antibodies measurement with Roche Elecsys Anti-SARS-CoV-2 S chemiluminescent immunoassay.ResultsThe median serum levels of total anti-SARS-CoV-2 antibodies reached the peak (1762 kU/L) 1 month after the second vaccine dose, but tended to progressively decline at the 3-month (1086 kU/L) and 6-month (802 kU/L) follow-up points. Overall, the values after 3and 6months were 37% and 57% lower than the corresponding concentrations measured at the peak. No healthcare worker had total anti-SARS-CoV-2 antibodies below the method-dependent cut-off after 6 months. The decline compared to the peak was more accentuated in baseline seropositive persons than in those who were baseline seronegative (74% vs. 52%) cohort. The 6-month post-vaccination anti-SARS-CoV-2 antibodies in subjects aged <65 years remained over 2-fold higher than in those aged ≥65 years (813 vs. 343 kU/L) and also remained consistently higher in women than in men.ConclusionsGradual decline of total anti-SARS-CoV-2 antibodies occurred 6 months after Pfizer-BioNTech COVID-19 vaccination, though values remained higher than the method-dependent cut-off, with no case of sero-negativization.
Highlights
There is consolidated evidence that the onset of SARS-CoV-2 infection in healthcare facilities is associated with an enhanced risk of morbidity and mortality, both in hospitalized patients as well as in healthcare workers
Since it is acknowledged that large part of vaccine effectiveness is attributable to the generation of anti-SARS-CoV-2 antibodies of different classes and with different antigenic targets (3), but capable to quickly and efficiently neutralize viral particles inside the host, regular assessment of these antibodies seems essential for monitoring immune protection among healthcare workers, especially given that serum levels of most vaccine-induced antibodies are observed to decline over time (4)
The study population consisted of 787 healthcare workers of Peschiera del Garda hospital in Italy, who received two 30 mg doses of Pfizer-BioNTech COVID19 vaccine, 3 weeks apart
Summary
There is consolidated evidence that the onset of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection in healthcare facilities is associated with an enhanced risk of morbidity and mortality, both in hospitalized patients as well as in healthcare workers. A recent study published by Yoshimura et al (2) evidenced a fairly good response in terms of anti-SARS-CoV-2 IgG level after a complete cycle of Pfizer BNT162b2 mRNA-based COVID-19 vaccine. Since it is acknowledged that large part of vaccine effectiveness is attributable to the generation of anti-SARS-CoV-2 antibodies of different classes and with different antigenic targets (3), but capable to quickly and efficiently neutralize viral particles inside the host, regular assessment of these antibodies seems essential for monitoring immune protection among healthcare workers, especially given that serum levels of most vaccine-induced antibodies are observed to decline over time (4). This study was aimed at monitoring the kinetics of serum total anti-SARS-CoV-2 antibodies in a cohort of healthcare workers who underwent voluntary administration of Pfizer-BioNTech COVID-19 mRNA-based vaccine
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