The Application of Sample Pooling for Mass Screening of SARS-CoV-2 in an Outbreak of COVID-19 in Vietnam

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  • 1 Centre for Disease Control and Prevention, Da Nang, Vietnam;
  • 2 Institute of Pasteur, Nha Trang, Vietnam;
  • 3 Viet A, Ho Chi Minh City, Vietnam;
  • 4 Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam;
  • 5 Da Nang University of Medical Technology and Pharmacy, Da Nang, Vietnam;
  • 6 Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam;
  • 7 Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom;
  • 8 Department of Health, Da Nang, Vietnam

We sampled nasal–pharyngeal throat swabs from 96,123 asymptomatic individuals at risk of SARS-CoV-2 infection, and generated 22,290 pools at collection, each containing samples from two to seven individuals. We detected SARS-CoV-2 in 24 pools, and confirmed the infection in 32 individuals after resampling and testing of 104 samples from positive pools. We completed the testing within 14 days. We would have required 64 days to complete the screening for the same number of individuals if we had based our testing strategy on individual testing. There was no difference in cycle threshold (Ct) values of pooled and individual samples. Thus, compared with individual sample testing, our approach did not compromise PCR sensitivity, but saved 77% of the resources. The present strategy might be applicable in settings, where there are shortages of reagents and the disease prevalence is low, but the demand for testing is high.

Author Notes

Address correspondence to Le Van Tan, Oxford University Clinical Research Unit, 764 Vo Van Kiet, District 5, Ho Chi Minh City, Vietnam. E-mail: tanlv@oucru.org

Disclosure: HTBT is the vice director of Viet A Company.

Financial support: The study was funded by Da Nang People’s Committee, Da Nang, Vietnam. L. V. T. and G. T. are supported by the Wellcome Trust of Great Britain (204904/Z/16/Z and 106680/B/14/Z, respectively).

Authors’ addresses: Ton That Thanh, Nguyen Thi Thanh Nhan, Le Thanh Chung, Nguyen Ngoc Anh, Bui Thuc Thang, Nguyen Thi Hoai Thu, and Le Thi Kim Chi, Centre for Disease Control and Prevention, Da Nang, Vietnam, E-mails: tonthatthanh9@gmail.com, thanhnhanytdpdn@gmail.com, lethanhchung65@yahoo.com.vn, dqanh103@gmail.co, buithucthang@gmail.com, nguyenhoaithu211088@gmail.com, and kimchile306@gmail.com. Huynh Kim Mai, Nguyen Bao Trieu, Le Xuan Huy, and Do Thai Hung, Institute of Pasteur, Nha Trang, Vietnam, E-mails: mai064@yahoo.com, baotrieuipn@yahoo.com.vn, lexuanhuy75@yahoo.com, and hungdt02@yahoo.com. Ho Thi Thanh Thuy, Viet A, Ho Chi Minh city, Vietnam, E-mail: httthuy@vietacorp.com. Nguyen Thi Thu Hong and Le Van Tan, Oxford University Clinical Research Unit, Ho Chi Minh, Vietnam, E-mails: hongntt@oucru.org and tanlv@oucru.org. Nguyen Thi Hanh and Nguyen Huy Hoang, Da Nang University of Medical Technology and Pharmacy, Da Nang, Vietnam, E-mails: nthanh@dhktyduocdn.edu.vn and nhhoang@dhktyduocdn.edu.vn. Nguyen Van Vinh Chau, Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam, E-mail: chaunvv@oucru.org. Guy Thwaites, Oxford University Clinical Research Unit, Ho Chi Minh city, Vietnam and Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom, E-mail: gthwaites@oucru.org. Ngo Thi Kim Yen, Department of Health, Da Nang, Vietnam, E-mail: yenntk@danang.gov.vn.

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