[Nosocomial influenza outbreak in a geriatrics department: Effectiveness of preventive measures]

To describe a nosocomial influenza outbreak and the pharmacologic and nonpharmacologic control measures implemented in a hospital ward with beds for acute geriatric care and rehabilitation care.

Descriptive survey conducted in the geriatrics department of a university hospital. An influenza outbreak occurred in February 2005 in 2 of the department's 3 separate units. The study concerned all patients in the 2 affected units (A and B) present during the outbreak, as well as all department staff. Once cases of influenza were confirmed, elderly patients in contact with influenza patients received chemoprophylaxis with oseltamivir when it became available.

Thirty-eight (76%) patients and 62 (38%) staff members had been vaccinated. The time from the initial symptoms of the first case until implementation of control measures was 7 days in unit A but only 1 day in unit B, -and chemoprophylaxis of contact patients began in 9 days and 24 hours respectively. The attack rate was 38% in the 38 vaccinated patients and 29% in the 14 unvaccinated patients (NS). All cases met the definition of nosocomial infection. No deaths imputable to influenza occurred during the outbreak. The implementation of the nonpharmacologic measures aimed at preventing spread of the outbreak presented no particular difficulty, except for compliance with geographic isolation of some patients with dementia and influenza. The difference between the attack rates for the two sectors (48% for unit A and 28% for unit B) suggests that the preventive measures were effective. Tolerance to chemoprophylaxis with oseltamivir was good.

This study confirmed that influenza can affect elderly hospital patients, even those in whom the vaccination rate is high, and that rapid detection of the outbreak and immediate implementation of pharmacologic and nonpharmacologic preventive measures can limit its spread.