Table 3. Pooled adjusted seasonal influenza vaccine effectiveness against hospitalised influenza A(H1N1)pdm09 overall among elderly people, by risk groups and vaccine type, I-MOVE + study, Europe, influenza season, 2015/16.
| Analyses | Model used for adjustmenta | Vaccinated /cases |
Vaccinated /controls |
Adjusted IVE | 95% CI |
|---|---|---|---|---|---|
| Overall | |||||
| Initial | 138/355 | 543/976 | 42.4 | 22.0 to 57.4 | |
| Full | 131/336 | 509/923 | 39.4 | 16.6 to 55.9 | |
| By risk groups | |||||
| At least one underlying condition | Initial | 130/317 | 499/892 | 35.7 | 11.4 to 53.3 |
| Initial plus severity | 35.6 | 11.2 to 53.3 | |||
| Diabetes mellitus | |||||
| No | Initial | 98/242 | 370/674 | 33.9 | 4.6 to 54.2 |
| Yes | Initial | 33/96 | 150/266 | 58.5 | 22.8 to 77.7 |
| Initial plus severity | 58.5 | 22.7 to 77.8 | |||
| Heart disease | |||||
| No | Initial | 54/131 | 207/372 | 37.3 | -1.2 to 61.1 |
| Yes | Initial | 80/211 | 321/581 | 38.4 | 6.5 to 59.5 |
| Initial plus severity | 39.0 | 7.3 to 59.9 | |||
| Lung disease | |||||
| No | Initial | 61/203 | 250/515 | 39.7 | 8.0 to 60.4 |
| Yes | Initial | 72/139 | 276/434 | 42.4 | 7.2 to 64.3 |
| Initial plus severity | 42.8 | 7.8 to 64.5 | |||
| Cancer | |||||
| No | Initial | 93/252 | 375/691 | 35.7 | 6.7 to 55.7 |
| Yes | Initial | 41/90 | 150/256 | 47.7 | 4.8 to 71.3 |
| Initial plus severity | 47.8 | 4.8 to 71.4 | |||
| Vaccine type | |||||
| Inactivated subunit | Initial | 77/224 | 209/538 | 28.1 | -8.6 to 52.4 |
| Inactivated split virion | Initial | 59/178 | 312/588 | 54.7 | 30.7 to 70.4 |
| Sensitivity analyses | |||||
| Two-stage model | two-stageb | 132/329 | 527/932 | 49.0 | 13.5 to 70.0 |
| Restricted to patients swabbed within 3 days | Initial | 85/216 | 313/518 | 49.1 | 23.8 to 66.0 |
| Restricted to patients not receiving antivirals before swabbing | Initial | 126/317 | 531/940 | 42.2 | 20.8 to 57.8 |
CI: confidence interval; I MOVE+: Integrated Monitoring of Vaccines in Europe plus; IVE: influenza vaccine effectiveness.
a Initial: one-stage model adjusted for study site, date of symptom onset and age (modelled as restricted cubic splines). Full: one-stage model adjusted for study site, date of symptom onset, age (modelled as restricted cubic splines), lung, heart, renal disease, diabetes mellitus, cancer, obesity (body-mass index ≥ 30 kg/m2) and hospitalisation for underlying conditions in past year. Severity: hospitalisations for underlying conditions in the previous year.
b Poland and Hungary were excluded because there were no vaccinated controls in Poland and no cases in Hungary.