ABSTRACT
Objectives: This research aimed to study the seroconversion among frontline staff at the highest risk of exposure to SARS-CoV-2 infections, including emergency department, critical care, and COVID-19 isolation wards in all healthcare job categories. Methods: We conducted a prospective cohort study on the incidence of seroconversion among frontline health care workers (HCWs) at the Royal Hospital, Muscat, Oman. Two sera were collected 12 weeks apart to look for seroconversion. We used proportions with 95% confidence interval (CI) for categorical data and mean/median as appropriate for continuous data. Results: Fourteen out of 328 HCWs seroconverted in this study accounting for an incidence rate of 3.6%, excluding four HCWs that were positive at baseline. The median age was 43.5 (range = 28-57). About 75.0% of HCWs were between 31-49 years old, with a seroconversion rate of 4.9% (95% CI: 2.7-8.1). Females accounted for most seroconverted HCWs (14/257) at a rate of 5.4% (95% CI: 3.1-8.8). Omanis seroconverted with a rate of 6.4% (95% CI 2.6-12.8), whereas non-Omanis seroconverted at a rate 4.3% (95% CI: 2.2-7.5). Ninety-two percent (302/328) of the staff lived in the capital area, and a minority lived outside the capital (3/26). Thirteen Muscat citizens seroconverted at a rate of 4.3% (95% CI: 2.4-7.1). Nurses comprised the majority (accounting for about 81%) followed by doctors (19%) at rates of 5.6% (95% CI: 3.2-9.2) and 4.2% (95% CI: 1.07-10.9), respectively. Staff covering COVID-19 isolation wards and intensive care unit comprised over 60% (n = 10) of those who seroconverted with a rate of 5.4% (95% CI: 2.8-9.5) followed by infectious diseases doctors and adult emergency at 19.0% (n = 3) and 12.5% (n = 1), respectively. Approximately 81.3% (n = 13) of HCWs performed aerosol-generating procedures at a seroconversion rate of 4.3% (95% CI: 2.4-7.1). About 50.0% of those who seroconverted had a positive polymerase chain reaction (PCR) before seroconversion, 25.0% had a negative PCR before second serology testing, and 25.0% were not tested with PCR. Approximately 20.0% of seroconverted staff had no reported symptoms compared to 80.0% who reported symptoms such as sore throat (70.0%), fever (50.0%), myalgia (20.0%), and a less frequency (15.0%) runny nose, loss of smell, and headache. Conclusions: Detection of infection among HCWs is important to prevent further transmission, especially asymptomatic carriers. A combined screening strategy of symptoms, serology, and PCR might help detect potential infections and asymptomatic carriage.