Table. Seropositivity at 60 Days, Symptom Prevalence, and Mean Signal-to-Threshold Values of Anti–SARS-CoV-2 Immunoglobulin Antibodies Among 19 Health Care Personnel Seropositive at Baseline.
| No. (%) | Signal-to-threshold value, mean (median)a | ||||
|---|---|---|---|---|---|
| SARS-CoV-2 ELISA results | Symptomaticb | Asymptomaticb | 0 d | 60 d | |
| Total reactive at baseline | 19 (100) | 11/19 (58) | 8/19 (42) | 2.8 (1.9) | 1.3 (1.0) |
| Total at 60 days | |||||
| Reactivea | 8/19 (42) | 6/8 (75) | 2/8 (25) | 4.8 (5.4) | 2.3 (2.7) |
| Nonreactive | 11/19 (58) | 5/11 (45) | 6/11 (55) | 1.4 (1.2) | 0.6 (0.7) |
Abbreviations: ELISA, enzyme-linked immunosorbent assay; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
a
A specimen was considered reactive if, on confirmatory testing, at a background corrected optical density above the threshold at a serum dilution of 1:100, it had a signal-to-threshold ratio greater than 1, which indicated anti–SARS-CoV-2 antibody presence.4
b
Symptomatic denotes those with symptoms of a viral respiratory illness, including fever, cough, shortness of breath, myalgias, sore throat, vomiting, diarrhea, dysgeusia, or anosmia, between February 1, 2020, and the baseline visit in April 2020. Others were classified as asymptomatic.