COVID-19 Serosurvey of Frontline Healthcare Workers in Western Australia.

We aimed to study COVID-19 infection in healthcare workers (HCWs) during the first wave in a setting of low community incidence prior to HCW vaccination. We performed a cross-sectional study of frontline HCWs in two tertiary hospitals in Western Australia with questionnaire and testing for SARS-CoV-2 IgG antibodies, using a screening assay followed by confirmatory assays for initial reactive results. 799 Frontline HCWs were enrolled in the study, working in the emergency department (n = 194, 24.2%), ICU (n = 176, 22.0%), respiratory ward (n = 20, 2.5%), COVID clinic (n = 37, 4.6%), and theatre (n = 222, 28%). 189 (23.6%) were doctors, 327 (41.0%) nurses, and 283 (35.4%) other. Contact with a known COVID-19-positive patient occurred at work for 337 (42.1%), and outside work for 10 (1.2%). Four were diagnosed with COVID-19 by PCR, acquired overseas in two cases and related to healthcare work in two cases (one acquired from a colleague and one possibly acquired from patient contact in the healthcare setting). Nine HCWs had reactive screening serology, and three had confirmed positive IgG (these three were PCR-positive cases). Infection control procedures in the setting of low community incidence were effective at preventing HCW acquisition of COVID-19 infection.