Effect Size of the Text Message Intervention on Receipt of Second Dose Influenza Vaccine by April 30 (Season End) and by Day 42 (2 Weeks After Second Dose Due) Post Vaccination, By Practices’ Typical Scheduling Approach for the Second Dose of Influenza Vaccine (Appointment Versus Walk-in) and Child Insurance Type (Commercial Versus Public and Uninsured)
| (B) End Point . | Practices’ Scheduling Approach and Child Insurance % (N) . | Arm . | Received Second Dose, % . | Difference % (95% Bootstrap CI) . |
|---|---|---|---|---|
| End of season | Appointment 75.5 (1574) | Intervention | 84.4 | 2.1 (−0.9 to 4.8) |
| Usual care | 82.3 | |||
| Walk-in 24.5 (512) | Intervention | 82.0 | 5.3 (0.5 to 9.4) | |
| Usual care | 76.7 | |||
| Day 42 post first Dose | Appointment 75.5 (1574) | Intervention | 64.5 | 5.1 (−0.2 to 10.0) |
| Usual care | 59.4 | |||
| Walk-in 24.5 (512) | Intervention | 55.7 | 11.3 (4.4 to 19.8) | |
| Usual care | 44.4 | |||
| End of Season | Commercial 54.5 (1137) | Intervention | 93.8 | 6.1 (3.2 to 9.0) |
| Usual care | 87.7 | |||
| Publicor uninsured 45.5 (948) | Intervention | 72.6 | 0.4 (−4.9 to 5.6) | |
| Usual care | 72.1 | |||
| Day 42 post first dose | Commercial 54.5 (1137) | Intervention | 75.0 | 8.8 (3.1 to 13.6) |
| Usual care | 66.2 | |||
| Public or uninsured 45.5 (948) | Intervention | 48.2 | 6.1 (−1.2 to 13.5) | |
| Usual care | 42.1 |
| (B) End Point . | Practices’ Scheduling Approach and Child Insurance % (N) . | Arm . | Received Second Dose, % . | Difference % (95% Bootstrap CI) . |
|---|---|---|---|---|
| End of season | Appointment 75.5 (1574) | Intervention | 84.4 | 2.1 (−0.9 to 4.8) |
| Usual care | 82.3 | |||
| Walk-in 24.5 (512) | Intervention | 82.0 | 5.3 (0.5 to 9.4) | |
| Usual care | 76.7 | |||
| Day 42 post first Dose | Appointment 75.5 (1574) | Intervention | 64.5 | 5.1 (−0.2 to 10.0) |
| Usual care | 59.4 | |||
| Walk-in 24.5 (512) | Intervention | 55.7 | 11.3 (4.4 to 19.8) | |
| Usual care | 44.4 | |||
| End of Season | Commercial 54.5 (1137) | Intervention | 93.8 | 6.1 (3.2 to 9.0) |
| Usual care | 87.7 | |||
| Publicor uninsured 45.5 (948) | Intervention | 72.6 | 0.4 (−4.9 to 5.6) | |
| Usual care | 72.1 | |||
| Day 42 post first dose | Commercial 54.5 (1137) | Intervention | 75.0 | 8.8 (3.1 to 13.6) |
| Usual care | 66.2 | |||
| Public or uninsured 45.5 (948) | Intervention | 48.2 | 6.1 (−1.2 to 13.5) | |
| Usual care | 42.1 |
Estimates for end of season, for which the follow up times differ across patients are based on a logistic regression, with confidence intervals estimated using 999 bootstrap samples (percentile method) in which resampling was done by practice site to reflect potential for clustering of patients within practice. Estimates of cumulative incidence at day 42 are based on survival curves using the method pseudo-values (Andersen et al), and confidence intervals are estimated using the same bootstrap sampling approach.