Table 4.
Questionnaire and survey-based studies
| Author | Age years | Type of study | Setting | Country | Children | Diagnostic test | Long COVID (N) | Long COVID (%) | Follow-up | Definition |
|---|---|---|---|---|---|---|---|---|---|---|
| Stephenson et al. [22] | 11–17 |
Prospective cohort study Control group |
Inpatients and outpatients CW |
England |
6804 tested 3065 positives 3739 negatives |
PCR | N/A |
66.5% PCR positive 53.4% PCR negative |
3 m | Presence of symptoms at 3 months post-testing |
| Molteni et al. [19] | 5–17 |
Prospective cohort study Control group |
Inpatients and outpatients SC CW |
UK |
1734 positives 1734 negatives |
PCR Serological test |
Positive: LC28 77 LC56 25 Negative with symptoms > 28 d: 15 |
Positive: LC28 4.4% LC56 1.8% Negative with symptoms > 28 d: 0.9% |
N/A |
Symptoms lasting > 28 days LC28 > 56 days LC56 |
| Radtke et al. [18] | Median age 11 IQR 9–13 |
Prospective cohort study Control group |
Inpatients and outpatients CW |
Switzerland |
109 positives 1246 negatives |
Serological test |
Symptoms over 4 w: 10 positive 121 negative Over 12 w: 4 positive 28 negative |
Symptoms over 4 w: 9% positive 10% negative Over 12 w: 4% positive 2% negative |
6 m | Symptoms lasting over 12 w |
| Miller et al. [20] | 0–17 |
Prospective cohort study Control group |
Outpatients MC CW |
UK |
175 positives 4503 negatives |
PCR (62.9%) Serological test (26.9%) Both (10.3%) |
80 |
1.7% overall 4.6% of positive |
3 m | Symptoms lasting over 4 w not explained by alternative diagnosis |
| Osmanov et al. [21] |
Median age 10.4 y (IQR 3–15) Range 2 d–18 y |
Prospective cohort study |
Inpatients SC HC |
Russia | 518 | PCR | 128 | 24.7% | Median 268 d (IQR 233–284) | Symptoms present at the time of follow-up interview and lasting over 5 months |
| Sterky et al. [14] | 0–18 | Prospective cohort study |
Inpatients MC HC |
Sweden |
55 53 After excluding PIMS-TS |
PCR |
6 4 After excluding PIMS-TS |
10% 7.5% After excluding PIMS-TS |
At least 4 m after admission (median 219 days, range 123–324 days) | Symptoms lasting at least 4 months after admission |
| Buonsenso et al. [27] | 11.4 SD 4.4 | Cross-sectional study |
Outpatients and inpatients SC HC |
Italy | 129 | PCR | 75 | 58.1% | Mean 162.5 d | Symptoms persisting over 30 d |
| Parisi et al. [30] | N/A |
Cross-sectional study Online survey to paediatricians |
Outpatients and inpatients HC |
Italy | 267 paediatricians | N/A | N/A | < 20% according to 97.3% of paediatricians | N/A | Persistence of symptoms after recovery (no timing expressed) |
| Brackel et al. [28] | Median age 13 (IQR 9–15) range 2–18 |
Cross-sectional study Survey to paediatricians |
Inpatients HC |
Netherlands | 78% of Dutch paediatric department |
PCR 47 (52.8%) Serology test 31 (34.8%) Clinical 34 (38.2%) |
89 | N/A | N/A | Symptoms persisting over 12 w and not explained by alternative diagnosis |
| Asadi-Pooya et al. [29] | 6–17 (mean 12.3 SD 3.31) | Cross-sectional study |
Inpatients MC HC |
Iran | 58 | PCR | 26 | 44.8% | 3 m | Symptoms persisting at least 3 months not present before acute COVID-19 |
| Ludvigsson [10] | 9–15 mean age 12 | Case series |
Inpatients and outpatients SC HC |
Sweden | 5 | Clinically diagnosed | 5 | N/A | N/A | Symptoms lasting over 2 months |
| Borch et al. [24] | Mean age 12 y (range 6–17) |
Retrospective cohort study Control group |
CW | Denmark |
Case group 15041 Control group 15080 |
PCR |
Case group (6–17 y) 3374 out of 12065 Control group (6–17 y) 2245 out of 8248 |
Case group (6–17 y) 28% Control group (6–17 y) 27.2% True long COVID prevalence estimated 0.8% |
4 w–13 m | Symptoms lasting at least 4 weeks after SARS-CoV-2 infection |
| Kikkenborg Berg et al. [32] |
Median age 17.6 y Range 16.5–18.6 y |
Cross-sectional study Control group |
CW | Denmark |
Case group 6630 Control group 21640 |
PCR |
Case group 3159 Control group 12340 |
Case group 61.9% Control group 57% |
12 m | At least one symptom lasting more than 2 m |
| Roge et al. [26] | 10 y; IQR 5–14 y; range 1 m–18 y |
Ambidirectional cohort study Control group |
Inpatients and outpatients SC HC |
Latvia |
Case group 236 Control group 142 |
PCR or serological test |
Case group 152 Control group 32 |
Case group 70% Control group 22.5 Estimated long COVID prevalence in Latvian children 1.09% |
73.5 d IQR 43–110 d | Symptoms experienced at least one m after acute illness |
| Zavala et al. [33] | Median age 10 (range 0–16) |
Cross-sectional study Control group Random selection of cases and controls |
Inpatients and outpatients SC CW |
England |
Case group 472 Control group 387 |
PCR |
Case group 21/320 Control group 6/154 |
Case group 6.7% Control group 4.2% |
3 m | Symptoms experienced at least 5 times at 1 month after SARS-CoV-2 infection |
N number, SC single centre, MC multi-centre, CW community-wide, HC health/hospital-centre, PCR polymerase chain reaction, N/A not applicable, m months, UK United Kingdom, d days, LC28 long COVID with symptoms persisting over 28 days, LC56 long COVID with symptoms persisting over 56 days, w weeks, IQR interquartile range, PIMS-TS paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2, SD standard deviations, y years, ISARIC International Severe Acute Respiratory and Emerging Infection Consortium