Table 2.
Characteristics of Included Studies.
| First Author | Country | Study design | Population | Aggregate study-level duration of virus detection since symptom onset from URT samples* | Aggregate study-level duration of virus detection since symptom onset from LRT samples* | Aggregate study-level duration of virus detection since symptom onset from stool sample* | Timing of Peak viral load in relation to symptom onset and day of testing (sample site) |
|---|---|---|---|---|---|---|---|
| An12 | China | Case series | 262 adults and children | Median between 15 and 20 days. Range, 5–47 days† | – | Median between 15 and 20 days. Range, 5–47 days† | – |
| Arons13 | US | Cross-sectional | 76 residents | – | – | – | 4 of 12 patients had VL peaking prior to symptom onset |
| Cai14 | China | Case series | 10 children | Median (IQR), 12 (8–15) days. Range, 6–22 | – | Range, 10 to >30 days (and still testing positive) | – |
| Cai15 | China | Case series | 298 adults | Median (IQR), 14 (10–20) days | – | – | – |
| Cao16 | China | RCT | 199 adults | – | – | – | Day of randomisation, which took place a median of 13 (IQR 11–16) days after symptom onset, 1st test (URT) |
| Chang17 | China | Case series | 16 adults and children | Median (IQR): 10.5 (6–12) days | – | – | – |
| Chen18 | China | Case report | 1 adult | 11 days | – | – | – |
| Chen19 | China | Case series | 249 adults | Median (95% CI), 11 (10–12) days | – | – | – |
| Chen20 | China | Case series | 57 patients (unknown age) | – | – | – | Days 10–12 of symptoms – 1st to 4th test (URT) |
| Chen21 | China | Case series | 42 adults | Median (IQR), 8 (5–12) days | Median, 9 days in uncomplicated, 8 (IQR 4.5‐14) days in mild, and 14 (IQR 9.5‐ 18) days in severe cases | – | |
| Cheng22 | Taiwan | Case series | 5 adults | 15 days | 15 days | – | Days 1–8 of symptoms −1st–3rd day of testing (URT). Days 1–6 of symptoms – 1st to 2nd test (LRT) |
| Cheng23 | Taiwan | Case-ascertained study | 2761 adults and children | – | – | – | – |
| Cheng24 | Taiwan | Case report | 1 adult | 20 days | 16 days | 24 days | – |
| Corman25 | Germany | Case series | 18 adults | – | – | – | Peak VL measured, but timing not reported (URT) |
| Fan26 | China | Case report | 1 child | 14 days | – | Still positive at 28 days | – |
| Fang27 | China | Case series | 32 adults | Mean ± SD, 17.3 ± 6.6 days | – | – | – |
| Fu28 | China | Case series | 50 adults | – | – | Median (IQR) 31 (IQR, 27–34 days)† | – |
| Gao29 | China | Case series | 2 adults | – | – | – | – |
| Gautret30 | France | NRCT | 36 adults and children | Median (IQR), 7 days (4.5–9.5) (however limited follow-up) | – | – | Day of randomisation, which took place an average of 4 (±2.6 SD) days after symptom onset, 1st test (URT) |
| Goh31 | Singapore | Case report | 1 adult | – | – | – | Day 10 of symptoms, 1st test (ETT) |
| He32 | China | Epidemiological modelling study | 94 adults | Approx. 21 days (using spline analysis) | – | – | Soon after symptom onset, 1st test (URT) |
| Hill33 | UK | Case report | 1 adult | 7.5 days | – | ND | Day 3 of symptoms, 1st test (URT) |
| Holshue34 | US | Case report | 1 adult | – | – | – | Day 4 of symptoms, 1st test (URT) |
| Hu35 | China | Cohort study | 59 adults | – | – | – | – |
| Hu36 | China | Case series | 24 adults and children | Median (IQR): 20.5 (16–26.25) days (from day of suspected exposure) | – | – | – |
| Huang37 | China | Case series | 33 adults and children | Median (IQR), 18.5 (13.25–22) days (from day of diagnosis) | Median (IQR), 22 (18.5–27.5) days (from day of diagnosis) | Median (IQR), 17 (11.5–32) days (from day of diagnosis) | 1st test (URT), 1st test (LRT), erratic peaking pattern (stool) |
| Jahan38 | Bangladesh | Case report | 1 adult | 10 days | – | – | – |
| Jiang39 | China | Case report | 1 child | – | – | 41 days (until first negative test) | – |
| Jing40 | China | Statistical transmission model | 349 adults and children | – | – | – | – |
| Jones41 | Germany | Cross-sectional | 3712 adults and children | – | – | – | Peak VL measured, but timing not reported (URT) |
| Kam42 | Singapore | Case report | 1 child | – | – | – | Day 1 of hospitalization, 1st test (URT); Day 8 of hospitalisation, 2nd test (stool) |
| Kim43 | South Korea | Case series | 2 adults | 14.5 days | 11.5 days | 9 days | Day 2 of symptoms, 1st test (URT); Day 5 of symptoms, 2nd test (LRT); Day 10 of symptoms, 6th test (stool) |
| Kujawski44 | US | Case series | 12 adults | 25 days (maximum) | 28 days (maximum) | 24 days (maximum) | VLs were lower in the first week of illness than the second in most patients (URT) |
| La Scola45 | France | Cross-sectional | 155 patients | 20 days (maximum)† | – | – | |
| Lavezzo46 | Italy | Cross-sectional | 2812 adults and children | Mean ± SD: 9.3 ± 2 days | – | – | – |
| Le47 | Vietnam | Case report | 1 child | 12 days | – | – | – |
| Le48 | Vietnam | Case series | 12 adults and children | Median (range): 8.5 (6–12) days | – | – | Peaked earlier in the disease trajectory (∼ 7 days after potential exposure) (URT) |
| Lee49 | Taiwan | Case report | 1 adult | 19 days | – | – | – |
| Lescure50 | France | Case series | 5 adults | 11 days | – | – | Days 2–9 of symptoms. 1st or 3rd tests, (URT). 1st or 2nd tests (Stool) |
| L'Huillier51 | Switzerland | Case series | 23 children | – | – | – | Peak VL measured, but timing not reported (URT) |
| Li52 | China | Case series | 36 adults | Median (IQR): 53.5 days (47.75–60.5) days | – | – | – |
| Li53 | China | Case series | 13 adults | Mean ± SD: 25 ± 6 days | 4 patients positive between 5 – 14 days after discharge | 2 patients tested positive 14 or 15 days after sputum tested negative. | – |
| Lillie54 | UK | Case series | 2 adults | 7.5 days | – | – | – |
| Lim55 | South Korea | Case report | 1 adult | – | 10 days | – | Day 9 of symptoms, 1st test (LRT) |
| Ling56 | China | Case series | 66 adults and children | Median (IQR) 9.5 (6.0–11.0) days. Range 2–22 days | – | Median (IQR): 11 (9.0–16.0) days | – |
| Liu57 | China | Case series | 10 adults | Median (IQR): 10 days (9–12) Range: 6–17 days (from first day of hospitalisation) |
– | – | – |
| Liu58 | Taiwan | Case report | 1 adult | 6 days | 44 days | Only detected in 1 sample before repeatedly testing negative thereafter | Day 1 of symptoms, 1st test (LRT) Day 2 of symptoms, 2nd test (URT) |
| Liu59 | China | Case series | 76 adults | – | – | – | Highest viral load detected on 1st test for majority of patients (URT). |
| Lo60 | China | Case series | 10 adults and children | Mean ± SD, 18.2 ± 4.6 days | – | Mean ± SD, 19.3 ± 3.4 days | – |
| Lv61 | China | Case report | 1 adult | 25 days | ND | ND | Day 16 of symptoms, 4th test (URT) |
| Ma62 | China | Case series | 8 adults and children | 2–3 weeks | – | Turned positive in weeks 3–5 and remained positive until end of follow up in 7 of 8 patients. | – |
| Marchand- Senécal63 | Canada | Case report | 1 adult | 7 days | – | – | Day 3 of symptoms, 2nd test (URT) |
| Meng64 | China | Case series | 42 adults | – | – | – | Day of peak VL not reported |
| Nicastri65 | Italy | Case report | 1 adult | 7 days (from first day of hospitalisation) | – | 9 days (from first day of hospitalisation) | – |
| Pan66 | China | Case series | 2 patients of unknown age (plus samples from 80 other patients) | 9 days | 10 days | ND | Days 5–6 of symptoms, 2nd or 3rd test (URT) |
| Paoli67 | Italy | Case report | 1 adult | 16 days | – | – | – |
| Peng68 | China | Case report | 2 adults and children | 15 days | – | ND | Day 6 of symptoms, 1st test (URT) |
| Pongpirul69 | Thailand | Case series | 11 adults | 14 days | – | – | – |
| Qian70 | China | Case report | 1 adult | 42 days | – | Only detected once | – |
| Qiu71 | China | Cohort study | 36 children | Mean ± SD, 10 ± 2 days, range 7–22 days (from first day of hospitalization) | – | – | – |
| Qu72 | China | Case report | 1 adult | 22 days | – | – | – |
| Saito73 | Japan | Case report | 1 adult | 15 days | – | – | – |
| Scott74 | US | Case report | 1 adult | 20 days (from day of diagnosis) | – | – | Day 1 and 6 of diagnosis, 1st and 2nd test (different URT samples) Day 8 of diagnosis, 2nd test (LRT) |
| Segar75 | US | Case report | 1 adult | 1 day | Positive on days 10 and 11 of symptoms | – | – |
| Shen76 | China | Case series | 5 adults | 24.5 days | – | – | Days 2–21 days of symptoms, 1st test for 2 patients, unknown number for others (URT) |
| Shi77 | China | Cross-sectional | 114 adults and children | – | – | – | – |
| Song78 | China | Case series | 24 adults and children | 15 days (from day of diagnosis) | – | – | – |
| Stebbing79 | Italy | Case series | 4 adults | 15 days | – | – | Days 1–16 of symptoms, 1st or 7th test (URT) |
| Su80 | China | Case series | 23 adults and children | 11.5 days (from day of hospitalisation for children) NR for adults |
ND in children NR for adults |
Turned positive for 5 discharged children NR for adults |
– |
| Tan81 | China | Case series | 142 adults | – | – | – | – |
| Tan82 | China | Case series | 2 adults | 38 days (range 24–52) | – | – | Day 27 of symptoms, 4th test (URT) |
| Tan83 | Vietnam | Case report | 1 adult | 15 days | – | 22 days | Day 6 of symptoms, 1st test (URT) Day 21 of symptoms, 12th (stool) |
| Tan84 | China | Case series | 13 children | 13 days (from day of diagnosis) | – | Only detected for unknown duration in 1 child | – |
| Tan85 | China | Case series | 10 children | 14 days | – | Detected inconsistently in 3 children | – |
| Thevarajan86 | Australia | Case report | 1 adult | 6 days | – | ND | Day 4 of symptoms, 1st test (URT) Day 6 of illness, 1st test (LRT and stool) |
| To87 | Hong Kong | Cohort study | 23 adults | - | – | – | Salivary VL was highest during the first week after symptom onset. |
| To88 | Hong Kong | Case series | 12 adults | – | – | – | 1st test (median of 2 days hospitalized) for all patients (except one where the VL was higher on 2nd test) (URT) |
| Tu89 | China | Case series | 40 adults | – | – | – | – |
| Wan90 | China | Case series | 2 adults | 15 days | – | – | 1st test for both asymptomatic patients (URT) |
| Wang91 | China | Cohort study | 4 adults | 19 days | 39 days | 1 patient was still testing positive after 35 days | – |
| Wang92 | China | Cohort study | 182 adults and children | 21 days (only provided for one patient) | – | Patient fluctuated between positive and negative anal swab results for 4 weeks after URT tested negative | – |
| Wang93 | China | Case series | 18 adults and children | 19.5 days | – | – | – |
| Wang94 | China | Case report | 1 adult | 32 days | – | – | – |
| Wei95 | Singapore | Case series | 18 adults | – | – | – | – |
| Wei96 | China | Case series | 84 adults | Mean ± SD, 12.5 ± 4 days, (for patients with diarrhoea). 9.2 ± 3.9 days (for patients without diarrhoea) |
– | Elimination from stool took longer than elimination from the nose and throat | – |
| Wei97 | China | Case series | 14 adults | 12 days (from day of diagnosis) | – | – | – |
| Woelfel98 | Germany | Case series | 9 adults | 9.5 days | 11.5 days | Persistently positive | Days 3–10 of symptoms, generally 1st test (URT) Days 2–11 of symptoms, generally 1st – 3rd test (LRT) Days 3–18 of symptoms, generally 1st – 3rd test (stool) |
| Wu99 | China | Case series | 74 adults | Mean ± SD, 16.1 ± 6.7 days | – | Mean ± SD, 27.9 ± 10.7 days | – |
| Xiao100 | China | Case series | 301 adults | 20 days | – | – | – |
| Xing101 | China | Case series | 2 adults | 17.5 days | – | – | – |
| Xing102 | China | Case series | 3 children | Median, 13 days (from first day of hospitalization) |
– | Median, 30 days (from first day of hospitalization) |
Day of admission,1st test (URT) Day 4 of hospitalisation, 2nd test (stool) |
| Xu103 | China | Cohort | 113 adults | – | 17 days† | – | – |
| Xu104 | China | Case series | 51 adults | – | – | – | Mostly highest in 1st tests |
| Xu105 | China | Case series | 15 adults and children | 7 days (from day of diagnosis)† | – | – | – |
| Xu106 | China | Case series | 10 children | Median (IQR), 5 (3.5–13.0) days | – | Median (IQR), 22 (7–23) days | Day of admission, 1st test (URT) Day 18 of hospitalisation, 18th test (stool) |
| Yan107 | China | Case series | 120 adults | Median (IQR), 23 (18–23) days | – | – | – |
| Yang108 | China | Case report | 1 adult | Still testing positive after 74 days since symptom onset | – | – | Day 36 of symptoms, 5th test (URT) |
| Yang109 | China | Case series | 55 adults and children | Mean (95% CI), 9.71 (8.21–11.22) days (since day of diagnosis)† | – | – | – |
| Yang110 | China | Case series | 82 adults | Median between 13 and 17 days | – | – | – |
| Yongchen111 | China | Case series | 21 adults and children | 14 days | – | 3 of 15 anal swabs remained positive after respiratory swab samples turned negative | – |
| Young112 | Singapore | Case series | 18 adults | Median, 11.5 days | – | – | Days 3–5 of symptoms, generally between 1st and 3rd test (URT) |
| Yu113 | China | Case series | 76 adults and children | – | – | – | VL higher in ‘early and progressive stages’ than ‘recovery stages’ (LRT) |
| Yu114 | China | Case series | 92 adults | – | – | – | VL highest at admission for patients admitted with severe disease. VL peaked at a later stage for patients admitted with mild-moderate disease who deteriorated (LRT) |
| Yuan115 | China | Case series | 25 adults and children | Median (IQR), 6 (4–10) days (time from initial negative result to testing positive again) | – | – | – |
| Yuan116 | China | Case series | 6 adults | Median (range), 9.5 (6–17) days (after the onset of treatment) | – | Stool samples were persistently positive in some patients | – |
| Zha117 | China | Case series | 31 adults | Median (IQR), 14 (11.5–16) days | – | – | – |
| Zhang118 | China | Case series | 23 adults | Median (IQR),10 (8 to 17) days | – | Median (IQR), 22 (15.5 - 23.5) days | Days 6–9 of symptoms, 1st or 2nd test (URT) Days 14–18 days of symptom onset, unclear number of tests (stool) |
| Zhang119 | China | Case series | 3 children | Median (range), 15 (14–25) days | – | Persistently positive | – |
| Zheng120 | China | Cohort study | 96 adults | Median (IQR), 18.5 (13–29) days† | – | Median (IQR), 22 (17–31) days (from day of diagnosis) | After week 2 of symptoms (LRT) During weeks 2–3 of symptoms (stool) |
| Zhou121 | China | Case series | 41 adults | Median (IQR), 31 (24–40) days | – | – | – |
| Zhou122 | China | Cohort study | 191 adults | Median (IQR) 20 (16 – 23) days | – | – | – |
| Zhu123 | China | Case series | 20 adults | Mean ± SD, 19.4 ± 10.7 days | – | – | – |
| Zou124 | China | Case series | 18 adults | – | – | – | Day 1 to 3 of symptoms, 1st or 2nd test (URT) |
Key: ETT - Endotracheal tube aspirate; Ct – cycle threshold; IQR – interquartile range; LRT – lower respiratory tract; ND – not detected; NRCT – non-randomized controlled trial; RCT – randomized controlled trial; URT – upper respiratory tract; VL – viral load.
*Viral clearance defined as two consecutive negative results with PCR detection at an interval of 24 h (counting the first day of negative results as the final day)
- Not measured by the study authors (site not tested, viral load not measured, or only tested on a single occasion).
†Site of sampling not distinguishable in this study.