Prevalence and Outcomes of SARS-CoV-2 Infection Among Migrant Workers in Singapore

Abstract

High-density communal residences are at elevated risk of large outbreaks of respiratory disease. 1,2 After an initial nationwide outbreak of 231 cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in Singapore, which was contained as of March 24, 2020, a surge of 244 cases among migrant workers residing in dormitories, largely from Bangladesh and India, occurred from March 25 to April 7. A national task force was formed to coordinate Singapore's outbreak response. A national lockdown from April 7 to June 1 enforced movement restriction and confined workers to their dormitories. Medical posts were deployed on-site in all dormitories, and testing capacity for testing and screening residents increased. All workers with a positive polymerase chain reaction (PCR) test result were admitted to health care facilities for isolation and treatment. We examined the prevalence and outcomes of SARS-CoV-2 infection among migrant workers in Singapore.

Highly functional virus-specific cellular immune response in asymptomatic SARS-CoV-2 infection

“…Longitudinal serology in asymptomatic SARS-CoV-2 infection Beginning in April 2020, Singapore experienced large outbreaks of SARS-CoV-2 infections among migrant workers residing in densely populated dormitories (Fig. 1 A; Tan et al, 2021b). To select asymptomatic individuals who were exposed to SARS-CoV-2 at different time points, we followed up on 478 residents of a SARS-CoV-2-affected dormitory who donated blood at recruitment and 2 and 6 wk later for serological testing of anti-NP IgG and neutralizing antibodies (nAbs; Fig.…”

“…The asymptomatic cohort comprised 541 men aged 19-59 yr (median 35 yr) recruited from randomly selected rooms within a SARS-CoV-2-affected dormitory housing >4,000 migrant workers largely from India and Bangladesh (∼86% ; Table S2) and followed up prospectively from May to July 2020 (Tan et al, 2021b). Detailed information about the measures to contain SARS-CoV-2 outbreaks in the dormitories can be found at the Singapore Ministry of Manpower website (https://www.mom.…”

“…In this work, we expand our investigation into virus-specific T cells in SARS-CoV-2 infection by studying asymptomatic SARS-CoV-2-infected individuals selected from a cohort of male foreign workers living in a Singapore dormitory (Tan et al, 2021b). Asymptomatic individuals constitute a variable but often large proportion of infected individuals (Lavezzo et al, 2020), and they should hold the key to understanding the immune response capable of controlling the virus without triggering pathological processes.…”

Contrasting SARS-CoV-2 Epidemics in Singapore: Cohort Studies in Migrant Workers and the General Population

“…Data from our study indicated that around two-thirds of dormitory residents had been infected between April and early July, in line with seroprevalence estimates reported from other migrant worker populations. 1 Moreover, our data suggest extremely high infection risks in these settings, with more than half of initially immunologically naive individuals becoming infected over the six-week follow-up period. Crowded, poorly ventilated indoor spaces are known to be high-risk environments for SARS-CoV-2 transmission, and have been associated with large outbreaks among processing plant workers.…”

“…However, from March 2020, Singapore experienced a series of large epidemics in densely populated migrant worker dormitories. 1 In response, workers were con ned to dormitories during the lockdown period and movement within dormitories was restricted. Medical teams were deployed in all dormitories to provide testing and refer suspected COVID-19 cases to healthcare facilities, leading to the eventual interruption of transmission in September 2020.…”