Table III.
Frequency and magnitude of SARS-CoV-2 viral RNA load in respiratory tract samples obtained from COVID-19 patients in selected studies
| Number of COVID 19 patients | Respiratory tract symptoms | Viral RNA load | Additional information | Reference |
|---|---|---|---|---|
| 76 | 74 with symptoms (97.4%) 2 without symptoms (2.6%) |
4.2 log10 cps∗ (sputum) 3.4 log10 cps∗ (throat) 2.8 log10 cps∗ (nasal) |
Viral RNA load high in early and progressive stage of COVID-19 | [16] |
| 9 | Not described | 5.5–5.8 log10 cps∗ (pharyngeal swab) 6.8 log10 cpm∗ (sputum) |
Lower viral RNA load in whole swab samples after day 5; infectious virus isolated by culture was only detected during the first week of symptoms (16.7% of swab samples; 83.3% in sputum samples); no isolates were obtained from samples taken after day 8 in spite of ongoing high viral RNA loads | [7] |
| 6 | 5 with symptoms (83.3%) 1 without symptoms (12.7%) |
1.0–4.0 log10 cpc (nasopharyngeal swab) 1.0–3.0 log10 cpc (nasopharyngeal swab) |
Viral secretion stopped after 5–17 days (median: 11 days) | [202] |
| 5 | All with symptoms | 1.0–7.4 log10 cpc (nasopharyngeal swab) | Viral RNA load decreased over time; 1 patient with virus detection after 24 days (death of patient) | [11] |
| 23 | All with symptoms | 4.1–7.0 log10 cpm (posterior oropharyngeal saliva)∗∗ | Old age was associated with high viral RNA load; salivary viral RNA load was highest during the first week after symptom onset; one patient had viral RNA detected for up to 25 days after symptom onset | [15] |
| 15 | All with symptoms | 4.6 log10 cpm (respiratory tract specimen) | None | [152] |
| 1 | With symptoms | 6.5 log10 cpm (pooled nasopharyngeal and throat swabs) 6.8 log10 cpm (sputum) |
None | [95] |
| 82 | With symptoms | 2.8–11.1 log10 cpm (1 nasal swab, 67 throat swabs and 42 sputum) | Median in sputum: 5.9 log10 cpm Median in throat samples: 4.9 log10 cpm |
[13] |
| 2 | All with symptoms | 4.7–7.7 log10 cpm (naso- and oropharyngeal swabs) 5.6–7.0 log10 cpm (sputum) |
None | [203] |
| 18 | 17 with symptoms (94.4%) 1 without symptoms (5.6%) |
Up to 7.2 log10 cpm (nasal and throat swabs) | Viral RNA load decreased over time | [5] |
cpc, copies per 1000 cells; cpm, copies per mL; cps, copies per whole swab or sample.
∗
Mean.
∗∗
Three patients with negative RNA test in saliva.