Table 2.
Risk factors for SARS-CoV-2 antibody positivity in students participating in school surveillance during the summer half-term (June to mid-July, 2020)
|
Antibody positive* |
Univariable analysis (n=816) |
Complete case univariable analysis adjusted for clustering by school (n=714) |
Multivariable analysis adjusted for clustering by school (p=1·00; n=714) |
|||||
|---|---|---|---|---|---|---|---|---|
| n/N (%)* | OR (95% CI) | p value† | OR (95% CI) | p value† | OR (95% CI) | p value† | ||
| Sex | .. | .. | 0·24 | .. | 0·21 | .. | 0·16 | |
| Female | 41/415 (9·9%) | 1 (ref) | .. | 1 (ref) | .. | 1 (ref) | .. | |
| Male | 50/401 (12·5%) | 1·30 (0·84–2·01) | .. | 1·35 (0·84–2·17) | .. | 1·42 (0·87–2·30) | .. | |
| Missing | 0 | NA | NA | NA | NA | NA | NA | |
| Age, years | .. | .. | 0·039 | .. | 0·049 | .. | 0·14 | |
| 4–6 | 27/322 (8·4%) | 1 (ref) | .. | 1 (ref) | .. | 1 (ref) | .. | |
| 7–9 | 34/220 (15·5%) | 2·00 (1·17–3·42) | .. | 2·03 (1·12–3·68) | .. | 1·79 (0·98–3·25) | .. | |
| ≥10 | 30/274 (10·9%) | 1·34 (0·78–2·32) | .. | 1·18 (0·63–2·19) | .. | 1·16 (0·63–2·14) | .. | |
| Missing | 0 | NA | NA | NA | NA | NA | NA | |
| Ethnicity | .. | .. | <0·0001 | .. | 0·0004 | .. | 0·0010 | |
| White | 37/497 (7·4%) | 1 (ref) | .. | 1 (ref) | .. | 1 (ref) | .. | |
| Mixed or multiple ethnic groups | 9/81 (11·1%) | 1·55 (0·72–3·36) | .. | 1·63 (0·73–3·65) | .. | 1·08 (0·47–2·49) | .. | |
| Black or Black British | 10/51 (19·6%) | 3·03 (1·41–6·54) | .. | 3·30 (1·41–7·75) | .. | 2·72 (1·13–6·59) | .. | |
| Asian or Asian British | 15/101 (14·9%) | 2·17 (1·14–4·13) | .. | 2·26 (1·12–4·56) | .. | 1·56 (0·76–3·23) | .. | |
| Other ethnic group | 20/75 (26·7%) | 4·52 (2·45–8·33) | .. | 4·45 (2·22–8·92) | .. | 4·02 (2·03–7·94) | .. | |
| Missing | 0/11 | NA | NA | NA | NA | NA | NA | |
| Region in England | .. | .. | 0·0002 | .. | 0·0056 | .. | 0·020 | |
| Derby | 14/154 (9·0%) | 0·61 (0·32–1·17) | .. | 0·64 (0·31–1·34) | .. | 0·48 (0·23–0·99) | .. | |
| East London | 23/105 (21·9%) | 1·71 (0·96–3·04) | .. | 1·69 (0·89–3·23) | .. | 1·48 (0·74–2·97) | .. | |
| Manchester | 15/192 (7·8%) | 0·52 (0·27–0·97) | .. | 0·65 (0·31–1·35) | .. | 0·72 (0·35–1·50) | .. | |
| North London | 37/262 (14·1%) | 1 (ref) | .. | 1 (ref) | .. | 1 (ref) | .. | |
| Oxford | 2/103 (1·9%) | 0·12 (0·03–0·51) | .. | 0·14 (0·03–0·67) | .. | 0·22 (0·05–0·97) | .. | |
| Attended school during lockdown | .. | .. | 0·40 | .. | 0·53 | .. | 0·13 | |
| No | 18/126 (14·3%) | 1 (ref) | 1 (ref) | .. | 1 (ref) | |||
| Yes | 71/613 (11·6%) | 0·79 (0·45–1·37) | 0·82 (0·45–1·51) | .. | 0·61 (0·32–1·15) | |||
| Missing | 2/77 (2·6%) | NA | NA | NA | NA | NA | NA | |
| Frequency of school attendance during lockdown | .. | .. | 0·52 | .. | .. | .. | .. | |
| Did not attend | 18/126 (14·3%) | 1 (ref) | .. | .. | .. | .. | .. | |
| ≥1 per week | 18/192 (9·4%) | 0·62 (0·31–1·24) | .. | .. | .. | .. | .. | |
| Less than half the week | 9/96 (9·4%) | 0·62 (0·27–1·45) | .. | .. | .. | .. | .. | |
| More than half the week | 18/136 (13·2%) | 0·92 (0·45–1·85) | .. | .. | .. | .. | .. | |
| Everyday | 26/189 (13·8%) | 0·96 (0·50–1·83) | .. | .. | .. | .. | .. | |
| Missing | 2/77 (2·6%) | NA | NA | .. | .. | .. | .. | |
| Previous confirmed COVID-19 in household | .. | .. | 0·007 | .. | .. | .. | .. | |
| No | 84/792 (10·6%) | 1 (ref) | .. | .. | .. | .. | .. | |
| Yes | 7/24 (29·2%) | 3·47 (1·40–8·61) | .. | .. | .. | .. | .. | |
| Number of children at home‡ | .. | .. | .. | .. | ||||
| Per one child increase in household | .. | 1·19 (0·96–1·48) | 0·12 | 1·14 (0·91–1·44) | 0·25 | 1·12 (0·89–1·42) | 0·33 | |
| Mean (SD) in negative households | 2·30 (0·93) | .. | .. | .. | .. | .. | .. | |
| Mean (SD) in positive households | 2·48 (1·12) | .. | .. | .. | .. | .. | .. | |
| Parental occupation | .. | .. | 0·0056 | .. | 0·0063 | .. | 0·0046 | |
| Not a health-care or key worker | 52/555 (9·4%) | 1 (ref) | .. | 1 (ref) | .. | 1 (ref) | .. | |
| Health-care worker | 23/115 (20·0%) | 2·42 (1·41–4·14) | .. | 2·58 (1·42–4·68) | .. | 2·66 (1·44–4·91) | .. | |
| Key worker (excluding health-care workers) | 16/146 (11·0%) | 1·19 (0·66–2·15) | .. | 1·10 (0·57–2·12) | .. | 1·01 (0·52–1·98) | .. | |
NA=not applicable. OR=odds ratio.
*
Unless otherwise specified.
†
Global p values calculated using the Wald test.
‡
60 children had missing data.