Anti-SARS-CoV-2 antibody testing is an efficient tool to assess the proportion of seropositive population due to infection and/or vaccination. Numerous test systems utilizing various antigen composition(s) are routinely used for detection and quantitation of anti-SARS-CoV-2 antibodies. We determined their diagnostic specificity using archived true-negative samples collected before the onset of the COVID-19 pandemic. Using test systems demonstrating 98.5–100% specificity, we assessed the dynamics of SARS-CoV-2 seroconversion and durability of anti-spike (S) antibodies in healthcare professionals ( n = 100) working in Moscow during the first two cycles of the pandemic (May 2020 to June 2021) outside of the “red zone”. Analysis revealed a rapid increase in anti-SARS-CoV-2 seropositivity from 19 to 80% (19/100 and 80/100, respectively) due to virus exposition/infection; only 16.3% of seroconversion cases (13/80) were due to vaccination, but not the virus exposure, although massive COVID-19 vaccination of healthcare workers was performed beginning in December 2020. In total, 12.7% (8/63) remained positive for anti-SARS-CoV-2 IgM for >6 months, indicating unsuitability of IgM for identification of newly infected individuals. All except one remained seropositive for anti-S antibodies for >9 months on average. Significant (>15%) declines in anti-SARS-CoV-2 antibody concentrations were observed in only 18% of individuals (9/50). Our data on the high seropositivity rate and stability of anti-SARS-CoV-2 antibody levels in healthcare personnel working outside of the “red zone” indicate their regular exposition to SARS-CoV-2/an increased risk of infection, while a low frequency of vaccine-induced antibody response acquired after the start of vaccination points to vaccine hesitancy.
【저자키워드】 COVID-19, antibodies, SARS-CoV-2, Healthcare workers, laboratory diagnosis, 【초록키워드】 IgM, Antibody testing, vaccination, pandemic, antibody, COVID-19 pandemic, Infection, diagnostic, virus, anti-SARS-CoV-2, Vaccine hesitancy, healthcare worker, Antigen, specificity, anti-SARS-CoV-2 antibodies, Seroconversion, stability, COVID-19 vaccination, anti-SARS-CoV-2 antibody, seropositive, Anti-spike, anti-SARS-CoV-2 IgM, Healthcare professional, Frequency, Concentration, healthcare personnel, Decline, increased risk, infected individuals, individual, average, rapid increase, quantitation, positive, anti-S antibody, vaccine-induced antibody response, collected, proportion, remained, was performed, Significant, Numerous, 【제목키워드】 Test, response, monitoring, assessment, application, worker,