All participants N=660 | Seronegative N=453 | Seropositive† N=207 | Adjusted difference‡ | |
Sex, N (%) | ||||
Female | 326 (49.4) | 229 (50.6) | 97 (46.9) | |
Age (mean, SD) | 9.3 (4.5) | 8.9 (4.7) | 10.2 (3.9) | – |
Age group in years, N (%) | – | |||
2–5 | 147 (22.3) | 118 (26.1) | 29 (14.0) | – |
6–11 | 271 (41.1) | 180 (39.7) | 91 (44.0) | – |
12–17 | 242 (36.6) | 155 (34.2) | 87 (42.0) | – |
Parental education§, N (%) | ||||
Tertiary | 386 (58.6) | 274 (60.6) | 112 (54.1) | – |
Secondary | 223 (33.8) | 145 (32.1) | 78 (37.7) | – |
Primary | 50 (7.6) | 33 (7.3) | 17 (8.2) | – |
Financial situation§, N (%) | ||||
High | 449 (68.1) | 316 (69.8) | 133 (64.3) | – |
Average to poor | 146 (22.1) | 92 (20.3) | 54 (26.1) | – |
Declined to answer | 65 (9.8) | 45 (9.9) | 20 (9.6) | – |
Anti-SARS-CoV-2 testing (PCR/antigen)¶ | 216 (32.7) | 80 (17.7) | 136 (65.7) | |
Hospitalisation due to COVID-19 | 0 | 0 | 0 | |
Symptoms>2 weeks | ||||
N (%) | 89 (13.5) | 50 (11.0) | 39 (18.8) | |
aPrev (95% CI)§ | 13.3 (10.4 to 16.2) | 11.1 (8.2 to 14.0) | 18.3 (13.0 to 23.6) | 7.2 (1.5 to 13.0)* |
Reported symptoms | ||||
Fatigue | ||||
N (%) | 52 (7.9) | 28 (6.2) | 24 (11.6) | |
aPrevalence (95% CI)§ | 7.3 (5.1 to 9.5) | 5.9 (3.7 to 8.1) | 10.3 (6.1 to 14.4) | 4.4 (0.2 to 9.0)* |
Respiratory | ||||
N (%) | 59 (8.9) | 35 (7.7) | 24 (11.6) | |
aPrev (95% CI)§ | 8.9 (6.4 to 11.3) | 7.6 (5.1 to 10) | 11.7 (7.3 to 16.1) | 4.1 (0.0 to 9.2) |
Gastrointestinal | ||||
N (%) | 41 (6.2) | 22 (4.9) | 19 (9.2) | |
aPrev (95% CI)§ | 5.7 (3.8 to 7.6) | 4.5 (2.6 to 6.4) | 8.4 (4.6 to 12.2) | 3.9 (0.3 to 8.1) |
Musculoskeletal | ||||
N (%) | 19 (2.9) | 7 (1.5) | 12 (5.8) | |
aPrev (95% CI)§ | 2.1 (1.2 to 3.1) | 1.1 (0.2 to 2.1) | 4.2 (1.4 to 7.1) | 4.2 (1.4 to 7.0)* |
Neurological | ||||
N (%) | 47 (7.1) | 20 (4.4) | 27 (13.0) | |
aPrev (95% CI)§ | 6.1 (4.3 to 7.9) | 3.8 (2.0 to 5.6) | 11.0 (6.7 to 15.4) | 7.2 (3.1 to 12.8)** |
Dermatological | ||||
N (%) | 16 (2.4) | 12 (2.6) | 4 (1.9) | |
aPrev (95% CI)§ | 2.3 (0.9 to 3.8) | 2.5 (1.0 to 4.0) | 1.9 (0.0 to 3.8) | −0.6 (−4.0 to 2.7) |
Symptoms’ duration | ||||
2–3 weeks | ||||
N (%) | 56 (8.5) | 24 (5.3) | 32 (15.5) | |
aPrev (95% CI)§ | 8.2 (6.2 to 10.3) | 5.2 (3.2 to 7.3) | 14.8 (9.9 to 19.7) | 9.6 (4.2 to 15.1)** |
3–4 weeks | ||||
N (%) | 8 (1.2) | 5 (1.1) | 3 (1.4) | |
aPrev (95% CI)§ | 1.0 (0.1 to 1.9) | 0.9 (0.0 to 1.8) | 1.0 (0.0 to 2.3) | 0.1 (−2.9 to 3.1) |
More than 4 weeks | ||||
N (%) | 20 (3.0) | 15 (3.3) | 5 (2.4) | |
aPrev (95% CI)§ | 3.0 (1.4 to 4.7) | 3.3 (1.7 to 5.0) | 2.4 (0.3 to 4.5) | −0.9 (−3.7 to 1.8) |
Symptoms impact on daily life | ||||
Low | ||||
N (%) | 71 (10.8) | 41 (9.1) | 30 (14.5) | |
aPrev (95% CI)§ | 10.7 (8.0 to 13.3) | 9.1 (6.4 to 11.7) | 14.2 (9.5 to 19.0) | 5.1 (−0.9 to 11.3)* |
High | ||||
N (%) | 34 (5.2) | 14 (3.1) | 20 (9.7) | |
aPrev (95% CI)§ | 4.7 (3.2 to 6.3) | 2.9 (1.3 to 4.5) | 8.6 (4.7 to 12.5) | 5.7 (2.2 to 9.9)* |
*P value<0.05.
†Seropositive is defined as naturally infected (Roche-N immunoassays cut-off index≥1.0).
‡Age-adjusted and sex-adjusted prevalence and prevalence differences, using marginal prediction of logistic regression and 95% CI were computed using normal approximation and truncated to 0 for the aPrev.
§Some of the children participating in the study are siblings therefore the reported parental and financial situation are presented individually.
¶The discrepancy between serological result and PCR+ might be related to test performances and errors while answering the questionnaire.
**P value<0.01.
aPrev, adjusted prevalence.