Table 1.
Study participation and incidence of SARS-CoV-2 infection by study site.
| Study participants | Participation ratea | Anti-SARS-CoV-2 nucleocapsid antibodies | |||
|---|---|---|---|---|---|
| Test number | Sample collection period | Positive | |||
| n (%) | % | n | Month year | n (%) | |
| All | 7808 (100.0) | 90.4 | 7780 | Jun 2021–Jan 2022 | 94 (1.2) |
| Hospital (location) | |||||
| National level | 1116 (14.3) | 85.7 | 1106 | 9 (0.8) | |
| NHTD (Hanoi) | 1116 (14.3) | 85.7 | 1106 | Jun 2021–Jan 2022 | 9 (0.8) |
| Provincial/city level | 4937 (63.2) | 89.6 | 4919 | 60 (1.2) | |
| QNGH (Quang Ninh) | 1189 (15.2) | 97.9 | 1188 | Sep–Nov 2021 | 17 (1.4) |
| HDHTD (Hai Duong) | 927 (11.9) | 82.1 | 911 | Jun–Aug 2021 | 2 (0.2) |
| DDGH (Hanoi) | 809 (10.4) | 92.1 | 809 | Sep 2021–Jan 2022 | 7 (0.9) |
| NAGH (Nghe An) | 658 (8.4) | 85.2 | 658 | Oct–Dec 2021 | 14 (2.1) |
| HYTD (Hung Yen) | 600 (7.7) | 95.2 | 600 | Sep–Dec 2021 | 4 (0.7) |
| 09 hospital (Hanoi) | 406 (5.2) | 85.8 | 406 | Sep–Dec 2021 | 8 (2.0) |
| HTCDC (Ha Tinh) | 348 (4.5) | 83.9 | 347 | Oct 2021–Jan 2022 | 8 (2.3) |
| District level | 1755 (22.5) | 96.5 | 1755 | 25 (1.4) | |
| NTL (Hanoi) | 1515 (19.4) | 98.4 | 1515 | Sep–Dec 2021 | 18 (1.2) |
| TSMC (Phu Tho) | 138 (1.8) | 89.0 | 138 | Oct 2021 | 2 (1.5) |
| YBMC (Yen Bai) | 102 (1.3) | 81.6 | 102 | Oct–Nov 2021 | 5 (4.9) |
aParticipation rate was calculated as the number of participants divided by the total number of outpatients under follow-up at each hospital.
Of all participants, only four (0.05%) and 42 people (0.5%) self-reported that they had ever been diagnosed with SARS-CoV-2 infection in a polymerase chain reaction (PCR) test or had been quarantined previously.
NHTD National Hospital for Tropical Diseases, QNGH Quang Ninh General Hospital, HDHTD Hai Duong Hospital for Tropical Diseases, DDGH Dong Da General Hospital, NAGH Nghe An General Hospital, HYTD Hung Yen Hospital of Tropical Diseases, 09 hospital 09 hospital, HTCDC Ha Tinh Center for Disease Control and Prevention, NTL Nam Tu Liem Health Center, TSMC Thanh Son District Medical Center, YBMC Yen Binh District Medical Center.