Background: Asymptomatic severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections are well documented . Healthcare workers (HCW) are at increased risk of infection due to occupational exposure to infected patients . We aim to determine the prevalence of SARS-CoV-2 antibodies among HCW who did not come to medical attention .

Methods: We prospectively recruited 400 HCW from the National Public Health Laboratory and two COVID-19 designated public hospitals in Klang Valley, Malaysia between 13/4/2020 and 12/5/2020 . Quota sampling was used to ensure representativeness of HCW involved in direct and indirect patient care . All participants answered a self-administered questionnaire and blood samples were taken to test for SARS-CoV-2 antibodies by surrogate virus neutralization test . Findings: The study population comprised 154 (38.5 %) nurses , 103 (25.8 %) medical doctors , 47 (11.8 %) laboratory technologists and others (23.9 %). A majority (68.9 %) reported exposure to SARS-CoV-2 in the past month within their respective workplaces . Adherence to personal protection equipment (PPE) guidelines and hand hygiene were good, ranging from 91-100% compliance . None (95% CI : 0 , 0.0095) of the participants had SARS-CoV-2 antibodies detected, despite 182 (45.5 %) reporting some symptoms one month prior to study recruitment . One hundred and fifteen (29 %) of participants claimed to have had contact with known COVID-19 persons outside of their workplace . Interpretation: Zero seroprevalence among HCW suggests a low incidence of undiagnosed COVID-19 infection in our healthcare setting during the first local wave of SARS-CoV-2 infection . The occupational risk of SARS-CoV-2 transmission within healthcare facilities can be prevented by adherence to infection control measures and appropriate use of PPE.