Successful interventions to control an influenza outbreak in an acute care facility

BACKGROUND: Healthcare-acquired (HA) influenza outbreaks are characterized by abrupt onset and rapid spread, with potentially devastating consequences for debilitated patients. We identified three HA influenza cases within 4 days on a 36-bed medical cardiology nursing unit of a 607-bed teaching hospital. METHODS: Upon identification of the second HA influenza case, an epidemiological investigation was conducted and control measures were implemented to halt the spread of influenza throughout the facility. All patients and healthcare workers (HCWs) on the unit were monitored for signs of respiratory illness. Patients with respiratory symptoms had a nasopharyngeal swab collected for rapid influenza testing and were placed in droplet precautions (DP). Chemoprophylaxis with amantadine was prescribed for all patients on the unit. Symptomatic HCWs were referred to occupational health (OH) for evaluation and testing. All employees of the unit were encouraged to be vaccinated and offered amantadine prophylaxis through OH. New admissions to the hospital with respiratory illness were placed in DP. All inpatients at the time of the outbreak, new admissions to the facility, and patients presenting to the emergency center were screened for influenza immunization and vaccinated if eligible for the duration of the influenza season. HCWs throughout the facility were strongly encouraged to take the influenza vaccine. OH nurses visited the various nursing units to vaccinate HCWs. To enhance case finding and to ensure implementation of DP, microbiology notified infection control of positive influenza testing on inpatients. Nursing managers were reminded to refer unusual staff absenteeism patterns to OH. RESULTS: Enhanced surveillance identified an additional case patient that developed influenza 1 day after discharge from the affected unit. The outbreak involved four patients. No HCWs from the affected unit tested positive for influenza. Following implementation of control measures, no further HA influenza cases were identified. CONCLUSION: Influenza can spread swiftly among patients and HCWs in acute care settings after introduction to the facility by infected visitors, patients, or staff. Prompt identification of an outbreak is critical to control HA influenza. Rapid initiation of an exposure investigation and successful implementation of infection control measures prevented a major influenza outbreak in our facility.