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Malaysia has experienced three waves of coronavirus disease 2019 (COVID‐19) as of March 31, 2021. We studied the associated molecular epidemiology and SARS‐CoV‐2 seroprevalence during the third wave. We obtained 60 whole‐genome SARS‐CoV‐2 sequences between October 2020 and January 2021 in Kuala Lumpur/Selangor and analyzed 989 available Malaysian sequences. We tested 653 residual serum samples collected between December 2020 to April 2021 for anti‐SARS‐CoV‐2 total antibodies, as a proxy for population immunity. The first wave (January 2020) comprised sporadic imported cases from China of early Pango lineages A and B. The second wave (March–June 2020) was associated with lineage B.6. The ongoing third wave (from September 2020) was propagated by a state election in Sabah. It is due to lineage B.1.524 viruses containing spike mutations D614G and A701V. Lineages B.1.459, B.1.470, and B.1.466.2 were likely imported from the region and confined to Sarawak state. Direct age‐standardized seroprevalence in Kuala Lumpur/Selangor was 3.0%. The second and third waves were driven by super‐spreading events and different circulating lineages. Malaysia is highly susceptible to further waves, especially as alpha (B.1.1.7) and beta (B.1.351) variants of concern were first detected in December 2020/January 2021. Increased genomic surveillance is critical. Highlights: As of March 2021, Malaysia has had 3 waves of COVID‐19The 2nd wave was driven by lineage B.6 virusesThe 3rd wave was driven by lineage B.1.524 virusesSeroprevalence in Kuala Lumpur/Selangor is only 3%Malaysia is susceptible to further waves [ABSTRACT FROM AUTHOR]

Seroprevalence studies provide a more accurate picture of coronavirus disease 2019 (COVID-19) than polymerase chain reaction (PCR)-confirmed cases as antibodies can be detected in mild or asymptomatic cases who otherwise remain undiagnosed. CI, confidence interval; COVID-19, coronavirus disease 2019 gl This study is potentially limited by bias arising from the use of residual inpatients serum. This is consistent with other seroprevalence studies revealing 6 to 24 times more COVID-19 infections than are reported.8 As this was a single-center study, a more extensive national serosurvey is necessary to confirm our preliminary indication that Malaysia has experienced limited SARS-CoV-2 transmission to date. [Extracted from the article]

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., Competing Interests: None of the authors have any conflict of interest, (© 2021 The Author(s).)