Unvaccinated workers pose flu risk in LTC

Deaths lower in hospitals with vaccinated workers

Carman WF, Elder AG, Wallace LA, et al. Effects of influenza vaccination of health-care workers on mortality of elderly people in long-term care: A randomized controlled trial. Lancet 2000; 355:93-97

Influenza vaccination of health care workers was associated with a near 9% decrease in mortality among patients in long-term care, the authors found. However, virological surveillance showed no associated decrease in non-fatal influenza infection in patients.

The potential is high for influenza to be brought into elderly-care homes by susceptible heath care workers and for infection to be transmitted to other heath care workers and to patients, the researchers noted. In a previous study, they found that vaccination of workers was associated with a decrease in mortality of elderly patients in long-term care from 17% to 10% over a winter season. In the current paper, they did a multicenter, randomized, controlled study to find out whether vaccination of health care workers would lower mortality and the frequency of laboratory-proven influenza infection in elderly patients in long-term-care hospitals.

In a parallel-group study, health care workers in 20 long-term elderly-care hospitals were randomly offered or not offered influenza vaccine. About 50% of the workers were immunized in the facilities where vaccine was offered, as opposed to only 5% of those in hospitals where it was not. All deaths among patients were recorded over six months in the winter of 1996-97.

The researchers selected a random sample of 50% of patients for virological surveillance for influenza, with combined nasal and throat swabs taken every two weeks during the epidemic period. Swabs were tested by tissue culture and PCR for influenza viruses A and B. The mortality rate in patients was 102 (13.6%) of 749 in vaccine hospitals compared with 154 (22.4%) of 688 in non-vaccine hospitals.