The seroprevalence of SARS-CoV-2 infection in Malaysia: 7 August to 11 October 2020

• Published in: Influenza and other respiratory viruses 2023-10, Vol.17 (10), p.e13193
• Main Authors: Chong, Zhuo-Lin, Rodzlan Hasani, Wan Shakira, Noor Asari, Filza, Muhammad, Eida Nurhadzira, Mutalip, Mohd Hatta Abdul, Robert Lourdes, Tania Gayle, Rifin, Halizah Mat, Singh, Sarbhan, Thayan, Ravindran
• Format: Article
• Language: English
• Subjects: Antibodies; Antibodies, Viral; Antigens; Asymptomatic; COVID-19; COVID-19 - diagnosis; COVID-19 - epidemiology; Cross-Sectional Studies; Data collection; Design analysis; Disease transmission; Enzyme-linked immunosorbent assay; Epidemiology; Humans; Infections; Institutionalization; Laboratories; Malaysia - epidemiology; Neutralization; Original; Pandemics; Phlebotomy; Population statistics; Public health; Quality control; Respiratory diseases; Sampling; Sampling designs; SARS-CoV-2; Seroepidemiologic Studies; Serology; Severe acute respiratory syndrome coronavirus 2; Vaccination; Variables; Viral diseases; Viruses
• ISSN: 1750-2640; 1750-2659; 1750-2659
• DOI: 10.1111/irv.13193

From the beginning of the COVID-19 pandemic until mid-October 2020, Malaysia recorded ~15,000 confirmed cases. But there could be undiagnosed cases due mainly to asymptomatic infections. Seroprevalence studies can better quantify underlying infection from SARS-CoV-2 by identifying humoral antibodies against the virus. This study was the first to determine the prevalence of SARS-CoV-2 infection in  Malaysia's general population, as well as the proportion of asymptomatic and undiagnosed infections. This cross-sectional seroprevalence study with a two-stage stratified random cluster sampling design included 5,131 representative community dwellers in Malaysia aged ≥1 year. Data collection lasted from 7 August to 11 October 2020 involving venous blood sampling and interviews for history of COVID-19 symptoms and diagnosis. Previous SARS-CoV-2 infection was defined as screened positive using the Wantai SARS-CoV-2 Total Antibody enzyme-linked immunosorbent assay and confirmed positive using the GenScript SARS-CoV-2 surrogate Virus Neutralization Test. We performed a complex sampling design analysis, calculating sample weights considering probabilities of selection, non-response rate and post-stratification weight. The overall weighted prevalence of SARS-CoV-2 infection was 0.49% (95%CI 0.28-0.85) (N = 150,857). Among the estimated population with past infection, around 84.1% (95%CI 58.84-95.12) (N = 126 826) were asymptomatic, and 90.1% (95%CI 67.06-97.58) (N = 135 866) were undiagnosed. Our study revealed a low pre-variant and pre-vaccination seroprevalence of SARS-CoV-2 infection in Malaysia up to mid-October 2020, with a considerable proportion of asymptomatic and undiagnosed cases. This led to subsequent adoption of SARS-CoV-2 antigen rapid test kits to increase case detection rate and to reduce time to results and infection control measures.