TABLE 2.
Longitudinal assessment of positive predictive agreement with an RT-PCR diagnosis for COVID-19 patientsa
| No. of days from diagnosis | No. of subjects |
Cumulative no. of S1/S2 IgG+ subjects/total | PPA (95%CI) | |||||
|---|---|---|---|---|---|---|---|---|
| First serial measurement |
Second serial measurement |
Third serial measurement |
||||||
| Total | S1/S2 IgG+ | Total | S1/S2 IgG+ | Total | S1/S2 IgG+ | |||
| ≤5 | 84 | 28 | 28/84 | 33.3 (23.4–44.5) | ||||
| 6–14 | 7 | 7 | 71 | 62 | 1 | 1 | 70/79 | 88.6 (79.5–94.7) |
| ≥15 | 13 | 13 | 12 | 12 | 22 | 20 | 45/47 | 95.7 (85.5–99.5) |
| Total no. of subjects | 104 | 83 | 23 | |||||
a
Serial samples from 104 COVID-19 patients positive by RT-PCR admitted to the hospital or ICU were tested with the LIAISON SARS-CoV-2 S1/S2 IgG assay. A value of 9 AU/ml was used as the cutoff for positivity. All samples in the same time brackets across measurements are from different patients, except for 3 samples from the third serial measurement at ≥15 days.