| Summary: | Intro: Coronavirus disease 2019 (COVID-19) began spreading in Malaysia since February 2020. Within months, the epidemic curve was flattened through strict public health measures and the number of confirmed cases remained low. But actual disease burden may be higher due to asymptomatic and undiagnosed COVID-19. This study aimed to determine the seroprevalence of COVID-19 and the proportion of asymptomatic and undiagnosed infections among Malaysia's general population. Methods: This cross-sectional seroprevalence study was conducted nationwide from 7 August to 11 October 2020. A two-stage stratified random cluster sampling design was used to select representative general populations aged ≥1 year-old. Participants provided their history of COVID-19 symptoms and diagnosis. Their blood specimens were tested with Wantai SARS-CoV-2 Total Antibody enzyme-linked immunosorbent assay first, and then GenScript SARSCoV-2 Surrogate Virus Neutralization Test. Participants with positive results on both tests were defined as having past COVID-19. Prevalence estimates and proportions were computed using complex sampling design analysis with weightage. Findings: A total of 5131 people participated, representing 30,763,427 of Malaysia's general population. The estimated population with past COVID-19 was 150,857, translating to an overall weighted COVID-19 seroprevalence of 0.49% (95%CI 0.28-0.85). Adults aged ≥18 year-old were significantly more likely to be infected (p=0.003), with 142,593 estimated past COVID-19 and 0.63% (95%CI 0.36-1.11) weighted prevalence. Among those with past COVID-19, the proportion of asymptomatic and undiagnosed infections was 84.1% (95%CI 58.9-95.1) and 90.1% (95%CI: 67.1-97.6), respectively. Discussion: COVID-19 seroprevalence in Malaysia up to early October 2020 was low, but higher among adults possibly due to higher mobility. High proportion of asymptomatic and undiagnosed infections pointed to underreporting and justified mass testing strategy using more cost-efficient SARS-CoV-2 antigen rapid test kits. Conclusion: The actual burden of COVID-19 was low but underreported in Malaysia during the first year of the pandemic. Repeated COVID-19 seroprevalence studies would be required as pandemic progresses.
|
|---|