Table 2.
Cluster composition by type of educational institution and role of SARS-CoV-2 index case, Germany, 2020
| Characteristic of index case | All types of secondary cases (n = 314)a | Student/child secondaries (n = 201) | Teacher secondaries (n = 113) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| N cases (clusters) | MSPIb | MSPI ratio [95% CI]c | P-valuec | N cases (clusters) | MSPIb | MSPI ratio [95% CI]c | P-valuec | N cases (clusters) | MSPIb | MSPI ratio [95% CI]c | P-valuec | ||
| All institutions | Student/child, n = 591 | 145 (76) | 0.25 | 1.00 | 120 (70) | 0.20 | 1.00 | 25 (16) | 0.04 | 1.00 | |||
| Teachers, n = 157 | 169 (48) | 1.08 | 4.39 [2.67–7.21] | <0.001 | 81 (37) | 0.52 | 2.54 [1.52–4.23] | <0.001 | 88 (32) | 0.56 | 13.25 [6.59–26.67] | <0.001 | |
| Day-care | Student/child, n = 79d | 52 (20) | 0.66 | 1.00 | 30d (15) | 0.38 | 1.00 | 22d (13) | 0.28 | 1.00 | |||
| Teachers, n = 113d | 142 (38) | 1.26 | 1.91 [0.95–3.84] | 0.07 | 67d (32) | 0.59 | 1.56 [0.78–3.13] | 0.21 | 75d (26) | 0.66 | 2.38 [1.04–5.49] | 0.04 | |
| Schools | Student/child, n = 474d | 82 (52) | 0.17 | 1.00 | 80d (51) | 0.17 | 1.00 | 2d (2) | 0.004 | 1.00 | |||
| Teachers, n = 32d | 16 (6) | 0.50 | 2.89 [0.99–8.44] | 0.05 | 14d (5) | 0.44 | 2.59 [0.86–7.83] | 0.09 | 2d (2) | 0.06 | 14.81 [2.09–105.15] | 0.007 | |
Table displays the mean number of SARS-CoV-2-PCR positive secondary cases per index case (MSPI), conditional on the role of the index case (i.e. student/child vs. teacher), and stratified by type of institution (day-care centre, school). For instance, independent of institution, the mean number of secondary cases in teachers is 0.04 and 0.56 for student/child and teacher-index cases, respectively, corresponding to an MSPI ratio of 13.3; the same comparison for day-care centres results in an MSPI ratio of 2.4.
36 index cases with missing age/role information.
Mean number of secondary cases per index case (MSPI).
MSPI ratio and corresponding confidence intervals (CIs) and P-values from negative binomial regression, modelling the difference in MSPI by category of index case, where an MSPI ratio of 1.0 corresponds to H0 = ‘no difference in the mean count of secondary cases between index categories’.
Number of subjects do not add up to total due to exclusion of cases that attended institutions other than schools and day-care centres (e.g. special needs schools).