Table 2. The effect of written information letters on influenza vaccination coverage conditional on prior vaccination history in a region with historically low vaccination coverage (Western region).
Influenza vaccination coverage (Western region) | ||||||
---|---|---|---|---|---|---|
Conditional on influenza vaccination 2017–2018 | Conditional on influenza vaccination 2011–2018 | Conditional on any vaccination 2011–2018 | ||||
(1) Vac. | (2) Unvac. | (3) Vac. | (4) Unvac. | (5) Vac. | (6) Unvac. | |
Regression Coef.: Effect of any reminder (vs. no reminder) | 0.019 (.017) | 0.088*** (.012) | 0.048** (.019) | 0.084*** (.011) | 0.050*** (.017) | 0.053*** (.013) |
Risk ratio: Effect of any reminder (vs. no reminder) | 1.021 (.018) | 1.824*** (.163) | 1.071** (.030) | 2.340*** (.312) | 1.131*** (.041) | 2.058*** (.417) |
Observations | 2196 | 5128 | 3243 | 4081 | 5308 | 2016 |
Coverage in control group (%) | 87.3% | 10.7% | 68.0% | 6.3% | 45.5% | 5.0% |
Notes: Reported regression coefficients are estimated using linear probability models. Reported risk ratio coefficients are estimated using Poisson regression. All models are estimated at the individual level. Standard errors in parentheses are clustered at the household level. Indicators for prior vaccination in Models 1 and 2: having vs. not having received influenza immunization during the previous seasonal influenza period (2017–2018); in Models 3 and 4: having vs. not having received any influenza immunization during the 9 years (2009–2018) prior to the influenza season of 2018–2019; Models 5 and 6: having vs. not having received any immunization during the 9 years (2009–2018) prior to the influenza season of 2018–2019.
*** p < 0.01
** p < 0.05, * p < 0.1.