Elderly populations are especially at risk during influenza season, partly because their aging immune systems don't respond well to vaccination. A total of 40 nursing homes in France took part in a study to determine whether raising flu vaccination rates among nursing home staff could affect the mortality rate among residents-as well as the rates of illness among both residents and staff. The homes were matched in pairs (according to size, extent of flu vaccine administered to staff during the 2005-2006 flu season, and acuity of the residents) and randomized. A total of 1,678 residents in the 20 control homes and 1,722 residents at the 20 intervention nursing homes were included in the study.

The intervention included a promotional campaign, informational meetings, and face-to-face interviews, all of which described the benefits of vaccination for both the staff and residents. After the interviews, staff were vaccinated if they chose to be. Staff in the control homes received standard information on the flu vaccine.

The average staff vaccination rate was 69.9% in the intervention homes and 31.8% in the control homes. A primary unadjusted analysis revealed no significant difference in mortality among the residents in the two study arms. The rate of flu-like illness, however, was significantly lower in the intervention arm; 8.7% of intervention-group staff took at least a day of sick leave, compared with 13.3% of control-group staff. Yet among control-group staff, those who received the vaccine were more likely to take sick leave than those who did not.

A multivariate analysis, which adjusted for age, vaccination, disability, and comorbidities among residents, showed a statistically significant 20% lower rate of death in the intervention arm, as well as a correlation between the percentage of staff who were vaccinated and residents' risk of dying. The authors of the study suggest that these findings demonstrate support for promoting vaccination of caregivers in nursing homes.

SDSJ