Seroprevalence of SARS-CoV-2 in Mazandaran province, Iran

Abstract

Objective: To determine the seroprevalance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in the general population of Mazandaran province in Iran and to estimate the percentage of asymptomatic, mild, and severe infections. Methods: We chose 1 588 inhabitants of Mazandaran province with cluster sampling. We measured their SARS-CoV-2 immunoglobulin M (IgM) and immunoglobulin G (IgG) serum levels. Demographics, risk factors, and symptoms were collected. The seroprevalence of SARS-CoV-2 was calculated by age and city and the World Health Organization (WHO) protocol and further stratified by demographic variables and risk factors. Finally, we identified the symptoms and factors related to COVID-19 with logistic regression. Results: Two hundred subjects (12.59%) were tested positive for either IgG or IgM. Until May 23, 2020, the prevalence of COVID-19 was 15.26% (95% CI: 12.97%-17.79%) based on direct standardization and WHO’s standardized age groups. Based on multivariate logistic regression, the incidence of getting an infection increased by an average of 11.6% for every 10-year increase in age (OR=1.116, 95% CI: 1.008-1.236, P=0.035). Furthermore, those in contact with COVID-19 patients had a 66.1% higher risk of developing the disease (OR=1.661, 95% CI: 1.104-2.497, P=0.015). In addition, the chance of getting SARS-CoV-2 infection was almost four times higher in people who had consulted a doctor during the pandemic than those who had not (OR=3.942, 95% CI: 2.813-5.524, P<0.001). Conclusions: The prevalence of COVID-19 in Mazandaran province could be higher than the officially reported statistics based on diagnostic tests and clinical cases. There seems to be more asymptomatic or mild symptom cases than what was previously reported.

Seroprevalence of SARS-Cov-2 Virus Infection In Kermanshah, Iran: A Population-based Cross-Sectional Study

“…In the present study, a geographical variation was observed in estimating the seroprevalence, which ranged from 2.3 to 61.6%. Our seroprevalence estimate was less than that reported from Semnan (19.3%, 95% CI, 14.0-26.7) in late June 2020 [14] and more than Mazandaran's 15.26% (95% CI: 12.97%-17.79%) in May 2020 [15]. Between April 17th and June 2nd, 2020, in a large and population-based seroprevalence study using obtained sera samples from 5372 individuals with a high risk of exposure to SARS-CoV-2 and 3530 individuals from the general population in 18 cities in 17 Iranian provinces, adjusted seroprevalence was estimated 20% (18.5-21.7) and 17.1% (95% CI 14.6-19.5) ranged from 72.6% (95% CI: 53.9-92.8) to 1.7% (95% CI: 0•0-6•0), respectively [16].…”

“…Z: for 95% confidence level is 1.96 P: Prevalence of positive COVID-19 based on the results of previous seroepidemiological studies in Kermanshah (15), which was 15%. d: d is the absolute precision, also called the margin of error, which was taken into account in a study of one-quarter of the prevalence, which was 0.0157.…”

“…The detection of SARS-CoV-2 specific IgG and IgM in blood serves as a method for determining whether the individual has been infected recently (IgM) or earlier (IgG); IgM usually increases after seven days of infection before increasing IgG. IgG is a longer-lasting antibody which develops 15 to 30 days after the onset of infection [11,15]. Notably, several studies have reported that approximately 38 to 48% of the population with seropositivity had no symptoms of Covid-19 [16 -18].…”