Table 4. Effectiveness of trivalent inactivated influenza vaccine in preventing influenza hospitalisation, influenza vaccine effectiveness study, Japan, November 2014 to March 2015 (n=3,228) .
| Influenza type | Vaccination status | No hospitalisation | Hospitalisation for influenza | Effectiveness in preventing influenza hospitalisation | 95% CI |
|---|---|---|---|---|---|
| Any Influenza | Unvaccinated | 1,447 | 236 | 55 | 43 to 64 |
| Vaccinated | 1,439 | 106 | |||
| Type A | Unvaccinated | 1,447 | 231 | 55 | 42 to 64 |
| Vaccinated | 1,439 | 104 | |||
| Type B | Unvaccinated | 1,447 | 5 | 60 | -108 to 92 |
| Vaccinated | 1,439 | 2 |
CI: confidence interval.