Table 1.
Characteristic of febrile outbreaks in school in Beijing, from August 2018 to July 2019.
| Characteristic | Mild Febrile Outbreaks (n = 354) |
Serious Febrile Outbreaks (n = 108) |
Total | Z/χ2 | p Value |
|---|---|---|---|---|---|
| Type of school 1 | |||||
| Primary school | 282 (77.90%) | 80 (22.10%) | 362 (100.00%) | 1.52 | 0.22 |
| Middle/high school | 72 (72.00%) | 28 (28.00%) | 100 (100.00%) | ||
| Areas 2 | |||||
| Urban | 205 (78.54%) | 56 (21.46%) | 261 (100.00%) | 1.24 | 0.27 |
| Rural | 149 (74.13%) | 52 (25.87%) | 201 (100.00%) | ||
| Male/female in febrile illnesses 2 | 1.17 (0.67–1.67) | 1.14 (0.79–1.42) | 1.14 (0.67–1.67) | 0.22 | 0.83 |
| Male/female of class 2 | 1.07 (0.95–1.21) | 1.10 (0.95–1.23) | 1.07 (0.95–1.21) | 0.55 | 0.58 |
| Number of students in class 2 | 39.00 (34–43) | 41.00 (37.0–45.5) | 39.00 (35–43) | 3.73 | 0.0002 |
| Subtype/lineage 1 | |||||
| B(Victoria) | 173 (78.28%) | 48 (21.72%) | 221 (100.00%) | 3.54 | 0.32 |
| A(H1N1)pdm09 | 53 (82.81%) | 11 (17.19%) | 64 (100.00%) | ||
| A(H3N2) | 110 (72.37%) | 42 (27.63%) | 152 (100.00%) | ||
| Other | 18 (72.00%) | 7 (28.00%) | 25 (100.00%) | ||
| Days from first case to intervention 2 | 3.00 (2.00–4.00) | 4.00 (3.00–5.00) | 3.00 (2.00–4.00) | 4.84 | <0.0001 |
| Influenza activity when outbreak reported 2,3 | 0.40 (0.30–0.55) | 0.44 (0.29–0.55) | 0.40 (0.29–0.55) | 0.44 | 0.66 |
| Vaccination coverage of class 2 | 0.39 (0.24–0.52) | 0.33 (0.21–0.47) | 0.37 (0.23–0.51) | 2.17 | 0.03 |
| Vaccination coverage of school 2 | 0.38 (0.31–0.47) | 0.36 (0.27–0.46) | 0.38 (0.30–0.47) | 1.98 | 0.047 |
1 Number of outbreaks and proportion were used to describe the variables, and the χ2 test was used to assess the difference between two groups. 2 Median and inter-quartile range were used to describe the variables and Wilcoxon’s test was used to assess the difference between two groups. 3 Influenza activity when outbreak reported: weekly positive proportion of influenza-like illness (ILI) for influenza in the district when outbreak was reported.