Estimate of anti-SARS-CoV-2 spike IgG antibodies prevalence among Iranian population based on blood donations: A serial cross-sectional study during the third wave of the pandemic.

ABSTRACT

OBJECTIVES: Iran is one of the countries that have been confronted with the SARS-CoV-2 epidemic since February 2020. This study aimed to determine the levels of specific IgG antibodies against SARS-CoV-2 among healthy blood donors to estimate the burden of the epidemic. MATERIAL AND METHODS: A serial cross-sectional study was conducted on blood donors who referred to 31 main blood donation centers in different provinces during the third weeks of September, October, and November 2020. A questionnaire was filled out to collect socio-demographic characteristics, history of contact with COVID-19 patients, and history of COVID-19. A blood sample was collected from each participant to assess the antibodies against SARS-CoV-2 using the ELISA method. The crude prevalence of anti-SARS-CoV-2 IgG was calculated. Then it was weighted based on the gender and age groups of the general population in each province and adjusted for test sensitivity and specificity. RESULTS: During three time points of the study, 3840, 3697, and 3152 participants enrolled. The seroprevalence of SARS-CoV-2 IgG antibodies was 19.59% (17.18-22.00), 22.67% (20.70-24.65), and 32.63% (29.93-35.33) over the three rounds of the study. We found an association between the seropositivity and the highest educational level; AOR 0.76 (0.63-0.93), history of close contact with COVID-19 patients; AOR 1.69 (1.35-2.11), and history of confirmed SARS-CoV-2 infection; AOR 8.86 (5.38-14.60). CONCLUSION: This study showed that about one-third of the population had been infected with COVID-19. Furthermore, a significant upward trend in seroprevalence was observed. The predisposing factors indicate the importance of public health.