Table I.
Proportion of asymptomatic carriers in selected COVID-19 cohorts
| Type of cohort | Size of cohort | Number of tested individuals | Number of positive tests (‘cases’) | Proportion of asymptomatic cases at the time of testing (N) | Reference |
|---|---|---|---|---|---|
| Hospitalized COVID-19 patients in Peking | 262 | 262 | 262 | 5.0% (13) | [57] |
| First 28 cases in South Korea | 28 | 28 | 28 | 10.7% (3) | [58] |
| Hospitalized COVID-19 patients in Wuhan | 81 | 81 | 81 | 18.5% (15) | [59] |
| Hospitalized COVID-19 children in Zhejiang | 36 | 36 | 36 | 27.8% (10) | [60] |
| Long-term care facility | 82 | 76 | 23 | 56.5% (13) | [61] |
| Family cluster | 9 | 9 | 8 | 25% (2) | [62] |
| Family aggregation | 7 | 7 | 7 | 57.1% (4) | [63] |
| Japanese nationals evacuated from Wuhan by chartered flights | 565 | 565 | 13 | 30.8% (4) | [65] |
| German nationals evacuated from Wuhan by chartered flights | 126 | 114 | 2 | 100% (2) | [66] |
| Passengers and crew members on board a cruise ship | 3711 | 3063 | 634 | 50.5% (320) | [67] |
| Children with known contact with persons having confirmed or suspected SARS-CoV-2 infection | 1391 | 1391 | 171 | 15.5% (27) | [64] |
| Iceland inhabitants with a high risk for infection | 9199 | 9199 | 1221 | 7%∗ | [68] |
| Iceland general population | 364000 | 13080 | 100 | 43%∗ | [68] |
| Children from family clusters | 74 | 74 | 74 | 29.7% (22) | [194] |
| Nursing facility | 89 | 76 | 48 | 56% (27) | [53] |
| Healthy passengers from cruise ship | 215 | 215 | 9 | 67% (6) | [195] |
| Asymptomatic healthcare workers | 1032 | 1032 | 30 | 57% (17) | [196] |
| Aircraft carrier | 382 | 382 | 238 | 18.5% (44) | [197] |
| Population of Vo’, Italy | 3276 | 2812∗∗ | 73 | 39.7% (29) | [198] |
| 2343∗∗∗ | 29 | 44.8% (13) |
∗
No absolute numbers reported.
∗∗
First survey.
∗∗∗
Second survey two weeks later.