SARS-CoV-2 antibody seroprevalence in industry workers in Split-Dalmatia and Sibenik-Knin County, Croatia

BACKGROUND As a result of global spread, COVID-19 has also affected the Republic of Croatia in the last week of February. Although official data show that the number of newly infected is declining, it is still unknown what proportion of the population has been affected by the disease. AIM To examine seroprevalence of SARS-CoV-2 antibodies in industry workers population sample. METHODS From 23 to 28 April 2020, we conducted serological testing for antibodies (IgG and IgM) on 1494 factory employees living in the Split-Dalmatia and Sibenik-Knin County (Croatia). We analysed antibody seroprevalence on the level of the company, county, and separately for employees living at the factory premises with limited mobility during the lockdown measures. RESULTS In a total sample of tested company employees, we detected antibodies in 1.27% of participants (95% CI 0.77-1.98%). In Split facility 13/1316 (0.99%, 95% CI 0.53-1.68%) of participants were tested positive, of which 13/1079 (1.20%, 95% CI 0.64-2.05%) of those living outside the facility and 0/237 (0%, 95% CI 0-1.26%) of those living inside the facility. In Knin facility, 6/178 (3.37%, 95% CI 1.25-7.19%) participants were tested positive for antibodies. The difference between Split (no mobility restrictions) and Knin, was not statistically significant (χ2 = 3.47, P = 0.062). CONCLUSIONS The study showed relatively small SARS-CoV-2 antibody seroprevalence in the DIV Group population sample. When the study findings are interpreted on the county levels, they could indicate that most of the counties9 population was not exposed to the virus.