Determinants and dynamics of the seroprevalence of anti-SARS-CoV-2 antibodies in Poland.

Abstract

Purpose: In the present study, we aimed to assess the anti-SARS-CoV-2 antibodies in population or in convalescents 6 months after infection with COVID-19.

Patients and methods: The study population consisted of 2 groups, i.e. group I: 232 post-COVID-19 patients, and group II: 544 patients from a population cohort. Detection of anti-N antibodies was performed with Elecsys Anti-SARS-CoV-2 and anti-S antibodies with LIAISON SARS-CoV-2 S1/S2 IgG tests.

Results: After the Omicron wave, gradual increase in the prevalence of the analyzed antibodies was observed in the general population - up to 92.5% of anti-S and 69.7% of anti-N antibodies. In the COVID-19 convalescents, 6 months after infection, 4.3% and 3.7% did not generate significant titer of anti-S and anti-N antibodies, respectively. Among patients, who were vaccinated, 1% did not generate anti-S antibodies. Median age of those who did not respond was higher than those who responded. Sex did not influence the results. Comparison of anti-N and anti-S antibodies 6 months after infection in the whole group showed higher anti-N titer in patients who suffered from the disease than in the general population. In the general population, 17.4% of participants had anti-N antibodies, and 9% had anti-S antibodies, despite no prior vaccination or history of COVID-19.

Conclusions: High prevalence of anti-N antibodies in patients reporting no history of COVID-19 during last wave, even after official end of the pandemics suggests high prevalence of SARS-CoV-2 in the environment and frequent asymptomatic or unspecific COVID-19, what is of high importance from the public health perspective.