TABLE 3.
Quasi-Poisson Regression of Predicted Secondary Cases and Relative Rate of Secondary Transmission by Masking Policy, Adjusted Per Capita and by Weeks Reporting to Study
| Masking Policy | Districts, n (%) | Students and Staff, n | Mean Primary Infections per 1000 Students and Staff per Week, n | Mean Secondary Infections per 1000 Students and Staff per Week, n | Predicted Secondary Cases per 100 Primary Cases | 95% CI | Relative Rate of Secondary Transmission | 95% CI |
|---|---|---|---|---|---|---|---|---|
| Universal | 46 | 1 227 131 | 2.7 | 0.16 | 5.8 | 3.62–9.27 | — | — |
| Partiala | 9 | 38 261 | 4.3 | 0.52 | 12.0 | 6.64–21.53 | 2.1 | 0.97–4.38 |
| Optional | 6 | 4576 | 5.4 | 2.33 | 43.5 | 30.99–61.10 | 7.5 | 4.21–13.42 |
CI, confidence interval; —, reference group for regression analysis.
a
Partial masking districts included: 4 districts that initially had optional masking and transitioned to masks required, 2 districts that transitioned between mask optional and required more than once during the study period, and 3 districts that had required and optional masking varying by either school grade level, or by community transmission threshold.