TABLE 1.
Characterization of the 4 SARS-CoV-2 School Outbreaks in Ontario, Canada, Occurring Between November 2020 to April 2021
| Outbreak Number | ||||
|---|---|---|---|---|
| 1 | 2 | 3 | 4 | |
| Total no. cases (n) | 53 | 37 | 21 | 21 |
| Staff (%) | 5 (9) | 8 (22) | 0 | 0 |
| Student (%) | 48 (91) | 29 (37) | 21 (100) | 12 (57) |
| Unknown (%) | 0 | 0 | 0 | 9 (43) |
| Symptom status | ||||
| Symptomatic (%) | 23 (43) | 13 (35) | 13 (62) | 8 (38) |
| Asymptomatic (%) | 30 (57) | 22 (60) | 3 (14) | 4 (19) |
| Unknown (%) | 0 | 2 (5) | 5 (24) | 9 (43) |
| No. cases sequenced | 25 | 34 | 8 | 12 |
| Complete genomic data* | 21 | 26 | 6 | 12 |
| Incomplete genomic data† | 4 | 8 | 2 | 0 |
| Clinical cohorts‡ | 28 | 16 | 8 | 10 |
| Median cases (range) | 1.5 (1–4) | 1.5 (1–8) | 2 (1–4) | 1 (1–2) |
| Genetic clusters§ | 7 | 3 | 3 | 4 |
*
Complete genomic data indicated by a SARS-CoV-2 genome coverage ≥90%.
†
Incomplete genomic data indicated by a SARS-CoV-2 genome coverage <90%.
‡
Clinical cohorts are based on epidemiologic data (eg, classroom).
§
Genetic clusters are based on SARS-CoV-2 sequence data, where the presence of ≤3 mutations, regardless of the identified Pango lineage, represents 1 genetic cluster.