BACKGROUND: Healthcare workers (HCWs) stand at the frontline for fighting coronavirus disease 2019 (COVID-19) pandemic. This puts them at higher risk of acquiring the infection than other individuals in the community. Defining immunity status among health care workers is therefore of interest since it helps to mitigate the exposure risk. STUDY DESIGN: Eighty-five hospitals across KSA were divided into two groups: COVID-19 referral hospitals are those to which RT-PCR-confirmed COVID-19 patients were admitted or referred for management (Case-hospitals). COVID-19 non-affected hospitals where no COVID-19 patients had been admitted or managed and no HCW outbreak (Control hospitals). Next, seroprevalence of SARS-CoV-2 among healthcare workers (HCWs) was evaluated; there were 12,621 HCWs from the 85 hospitals. RESULT: There were 61 case-hospitals with 9,379 (74.3%) observations, and 24 control-hospitals with 3,242 (25.7%) observations. The overall positivity rate by the immunoassay was 299 (2.36%) with a significant difference between the case-hospital (2.9%) and the control-group (0.8%) (P value <0.001). There was a wide variation in the positivity rate between regions/cities in Saudi Arabia, ranging from 0% to 6.31%. Of the serology positive samples, 100 samples were further tested using the SAS2pp neutralisation assay; 92 (92%) samples showed neutralisation activity. CONCLUSION: The seropositivity rate in KSA is low and varies across different regions with higher positivity in case-hospitals than control-hospitals. The lack of NAb in 8% of the tested samples could mean that assay is a more sensitive assay or that neutralisation assay has a lower detection limits; or possibly that some samples had cross-reaction to spike protein of other coronaviruses in the assay, but these were not specific to neutralize SARS-CoV-2.
Seroprevalence of SARS-CoV-2 (COVID-19) among Healthcare Workers in Saudi Arabia: Comparing Case and Control Hospitals