Table 2 Association factors to the number of secondary cases generated, Kamigoto island, Japan, 2010/11–2017/18.
From: Transmission dynamics of seasonal influenza in a remote island population
Variable | Secondary cases | IRR | 95% CI | p-value |
|---|---|---|---|---|
Intercept | 0.01 | (0.01, 0.03) | < 0.001** | |
Age group, years | ||||
< 3 | 0.95 | (0.78, 1.14) | 0.574 | |
4–6 | 1.38 | (1.21, 1.57) | < 0.001** | |
7–12 | 1.45 | (1.33, 1.59) | < 0.001** | |
13–18 | 1.51 | (1.37, 1.66) | < 0.001** | |
19–64 | 1 | Reference | ||
65–74 | 0.72 | (0.58, 0.89) | 0.002* | |
≥ 75 | 0.76 | (0.63, 0.91) | 0.003* | |
RDT results | ||||
Flu A | 1 | Reference | ||
Flu B | 0.83 | (0.77, 0.90) | < 0.001** | |
Not attributed | 0.68 | (0.48, 0.98) | 0.037* | |
Vaccination history | ||||
No | 1 | Reference | ||
Yes | 1.06 | (0.96, 1.17) | 0.278 | |
Unknown | 1.10 | (0.95, 1.27) | 0.213 | |
Mean household size | 1.04 | (0.66, 1.62) | 0.873 | |
Population per district | 2.00 | (1.89, 2.12) | < 0.001** | |
Proportion unvaccinated in the district | 1.45 | (1.02, 2.05) | 0.037* | |
Average proportion unvaccinated in neighboring districts | 2.41 | (1.11, 5.21) | 0.026* | |
Influenza season | ||||
2010/11 | 1 | Reference | ||
2011/12 | 0.87 | (0.76, 1.00) | 0.044 | |
2012/13 | 0.96 | (0.84, 1.10) | 0.580 | |
2013/14 | 0.95 | (0.84, 1.09) | 0.476 | |
2014/15 | 0.90 | (0.79, 1.03) | 0.141 | |
2015/16 | 1.28 | (1.06, 1.54) | 0.010* | |
2016/17 | 0.91 | (0.79, 1.06) | 0.232 | |
2017/18 | 1.31 | (1.10, 1.57) | 0.003* | |
Seasonality | ||||
Sin | 0.99 | (0.95, 1.04) | 0.769 | |
Cosin | 1.01 | (0.96, 1.05) | 0.823 | |
