Experience with oseltamivir in the control of nursing home influenza A outbreak

OBJECTIVE: Influenza outbreaks have revealed that elderly persons are a great risk of death and serious complications after infection. The administration of oseltamivir, a neuramidase inhibitor, is effective for prophylaxis of influenza and to reduce disease duration and severity in healthy adults with naturally acquired febrile influenza. To clarify the usefulness of oseltamivir in the elderly we administered oseltamivir to all residents when an influenza A outbreak occurred in a nursing home. PATIENTS: Sixty-eight residents in the nursing home were investigated in which the influenza A outbreak occurred; 32 residents had fever and 28 residents were positive for influenza A with direct enzyme immunoassay. METHODS: Oseltamivir was administered at 75 mg twice daily for 5 days to all residents. RESULTS: Oseltamivir almost inhibited symptom onset in the influenza A-positive afebrile group. Initiation at 0 hour (22 cases), 1-12 hours (4 cases), 13-24 hours (5 cases) or 72 hours (1 case) from onset of symptoms was associated with mean fever durations of 26+/-18 hours, 38+/-21 hours, 54+/-12 hours and 120 hours, respectively, indicating that earlier initiation of therapy was associated with faster resolution of fever in elderly patients. Oseltamivir may be effective for household prophylaxis in the elderly persons. Oseltamivir administration was well tolerated in elderly persons. CONCLUSION: Oseltamivir is effective for the reduction or prophylaxis of influenza A infection in elderly persons.