COVID-19 outbreak at a reception centre for asylum seekers in Espoo, Finland

Abstract

\n \n Background: Shared accommodation may increase the risk of SARS-CoV-2 transmission. In April 2020, an increasing number of asylum seekers at a reception centre in Espoo, Finland presented with COVID-19 despite earlier implementation of preventive measures. We decided to screen the entire population of the centre for SARS-CoV-2.\n \n Methods: We offered nasopharyngeal swab collection and SARS-CoV-2 real-time polymerase chain reaction (RT-PCR) analysis to the centre s clients. Symptoms were recorded at the time of diagnostic sample collection using electronic forms and followed up for two weeks through phone interviews and a review of medical records.\n \n Findings: 260 clients were screened. Of them, 96 (37%) were found positive for SARS-CoV-2 and isolated. The high attack rate prompted the local public health authority to set the other clients in quarantine for 14 days to prevent further spread. Of the positive cases, 61 (64%) reported having had symptoms at the time of the screening or one week prior. Of the 35 initially asymptomatic individuals, 12 developed symptoms during follow-up, while 23 (or 18% of all screened SARS-CoV-2 positive clients) remained asymptomatic. No widespread transmission of COVID-19 was detected after the quarantine was lifted.\n \n Interpretation: In this large COVID-19 outbreak, voluntary mass screening provided valuable information about its extent and helped guide the public health response. Comprehensive quarantine and isolation measures were likely instrumental in containing the outbreak.\n \n Funding: Finnish Institution for Health and Welfare, Finnish Immigration Agency, City of Espoo\n