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Lancet Infect Dis. 2020 Apr 21. pii: S1473-3099(20)30273-5. doi: 10.1016/S1473-3099(20)30273-5. [Epub ahead of print]
Connecting clusters of COVID-19: an epidemiological and serological investigation.
Yong SEF1, Anderson DE2, Wei WE3, Pang J4, Chia WN2, Tan CW2, Teoh YL5, Rajendram P6, Toh MPHS7, Poh C6, Koh VTJ6, Lum J6, Suhaimi NM6, Chia PY8, Chen MI7, Vasoo S8, Ong B9, Leo YS8, Wang L2, Lee VJM10.
Author information
Abstract
BACKGROUND:
Elucidation of the chain of disease transmission and identification of the source of coronavirus disease 2019 (COVID-19) infections are crucial for effective disease containment. We describe an epidemiological investigation that, with use of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serological assays, established links between three clusters of COVID-19.
METHODS:
In Singapore, active case-finding and contact tracing were undertaken for all COVID-19 cases. Diagnosis for acute disease was confirmed with RT-PCR testing. When epidemiological information suggested that people might have been nodes of disease transmission but had recovered from illness, SARS-CoV-2 IgG serology testing was used to establish past infection.
FINDINGS:
Three clusters of COVID-19, comprising 28 locally transmitted cases, were identified in Singapore; these clusters were from two churches (Church A and Church B) and a family gathering. The clusters in Church A and Church B were linked by an individual from Church A (A2), who transmitted SARS-CoV-2 infection to the primary case from Church B (F1) at a family gathering they both attended on Jan 25, 2020. All cases were confirmed by RT-PCR testing because they had active disease, except for A2, who at the time of testing had recovered from their illness and tested negative. This individual was eventually diagnosed with past infection by serological testing. ELISA assays showed an optical density of more than 1?4 for SARS-CoV-2 nucleoprotein and receptor binding domain antigens in titres up to 1/400, and viral neutralisation was noted in titres up to 1/320.
INTERPRETATION:
Development and application of a serological assay has helped to establish connections between COVID-19 clusters in Singapore. Serological testing can have a crucial role in identifying convalescent cases or people with milder disease who might have been missed by other surveillance methods.
FUNDING:
National Research Foundation (Singapore), National Natural Science Foundation (China), and National Medical Research Council (Singapore).
Copyright ? 2020 Elsevier Ltd. All rights reserved.
PMID:32330439DOI:10.1016/S1473-3099(20)30273-5