Table 2. Evidence supporting positive test results indicating presence of virus and impact on other factors.
| Strength of evidence for true infection | ||||
|---|---|---|---|---|
| Higher | Moderate | Lower | p (exact) | |
| Number (col %) (N = 27,879) | 21,329 (77%) | 4741 (17%) | 1809 (6%) | |
| Factors determining classification | ||||
| Number of genes detected (row %) |
3: 10,317 (48%) 2: 11,012 (52%) |
1: 4741 (100%) | 1: 1809 (100%) | |
| CT, median | 26.2 | 33.4 | 34.8 | |
| CT, n (row %) <34* | 21,070 (98.8%) | 3613 (76%) | 0 (0%) | |
| Symptoms around test, n (row %) | 12,466 (58%) | 2243 (47%) | 0 (0%) | <0.0001 (exc lower) |
| Occupational risk†, n (row %) | 1322 (6%) | 307 (6%) | 0 (0%) | 0.48 (exc lower) |
| Other factors | ||||
| Cough, fever, anosmia, ageusia around test, n (row %) | 9345 (44%) | 1241 (26%) | 0 (0%) | <0.0001 (exc lower) |
| First positive test n (row %) (vs subsequent positive test) | 16,709 (78%) | 3508 (74%) | 1594 (88%) | <0.0001 |
| First test in study, n (row %) (vs follow-up i.e. prior negative in study) | 2281 (11%) | 482 (10%) | 199 (11%) | 0.49 |
| Any genome sequence obtained, confirming presence of virus‡ | 6,621/9,022 (73%) | 544/2,315 (24%) | 0/836 (0%) | <0.0001 |
| Any other household member ever positive$ | 11,493/18,494 (62%) | 1,513/4,004 (38%) | 318/1,525 (21%) | <0.0001 |
*Approximate 97.5th percentile of CT in higher evidence positives through 2 August 2020 when classification first applied.
†Reported working in a patient-facing healthcare role/care/residential home.
‡Any genome sequence obtained out of attempted (other positives not found or not yet attempted).
$Denominator households with two or more study participants.
Note: Classification arbitrarily determined on 2 August 2020 based on the number of genes detected, Ct values and pre-test probability (see Materials and methods).