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.