Long-term use of oseltamivir for the prophylaxis of influenza in a vaccinated frail older population.
OBJECTIVE
To investigate the efficacy of once-daily oral oseltamivir for 6 weeks (Tamiflu) in prophylaxis against laboratory-confirmed clinical influenza in frail older subjects living in homes for seniors and to determine the safety and tolerability of long-term oseltamivir.


METHODS
Double-blind, placebo-controlled, parallel-group, randomized, multicenter study.


METHODS
Thirty-one residential homes for seniors across United States and Europe.


METHODS
Five hundred forty-eight frail older occupants (mean age 81 years, >80% vaccinated).


METHODS
Prophylaxis with oseltamivir 75 mg or placebo once daily for 6 weeks, beginning when influenza was detected locally.


METHODS
The primary efficacy endpoint was laboratory-confirmed clinical influenza.


RESULTS
Oseltamivir administration resulted in a 92% reduction in the incidence of laboratory-confirmed clinical influenza compared with placebo (placebo 12/272 (4.4%), oseltamivir 1/276 (0.4%); P = .002). Of subjects vaccinated against influenza, oseltamivir was 91% effective in preventing laboratory-confirmed clinical influenza (placebo 11/218 (5.0%), oseltamivir 1/222 (0.5%); P = .003). Oseltamivir use was associated with a significant reduction in the incidence of secondary complications (placebo 7/272 (2.6%), oseltamivir 1/276 (0.4%); P = .037). Although nearly all subjects were taking concomitant medication both before and during the study, oseltamivir was well tolerated. A similar incidence of adverse events, including gastrointestinal effects, occurred in both groups. There was no suppression of antibody response in oseltamivir recipients.


CONCLUSIONS
Oral oseltamivir 75 mg once daily for 6 weeks effectively prevented clinical influenza in vaccinated frail older subjects using significant concomitant medications in a residential care setting. The treatment was well tolerated and provided additional protection to that afforded by vaccination.
Peters
P H
PH
Protocare Trials at the San Antonio Center for Clinical Research, San Antonio, Texas, USA.
Gravenstein
S
S
Norwood
P
P
De Bock
V
V
Van Couter
A
A
Gibbens
M
M
von Planta
T A
TA
Ward
P
P
D000081:Acetamides / Q000009:adverse effects / Q000627:therapeutic use*; D000368:Aged; D000369:Aged, 80 and over; D000998:Antiviral Agents / Q000009:adverse effects / Q000627:therapeutic use*; D004311:Double-Blind Method; D005060:Europe / Q000453:epidemiology; D005260:Female; D016330:Frail Elderly; D006707:Homes for the Aged; D006801:Humans; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control*; D008297:Male; D009439:Neuraminidase / Q000037:antagonists & inhibitors*; D053139:Oseltamivir; D014481:United States / Q000453:epidemiology
D000081:Acetamides; D000998:Antiviral Agents; D053139:Oseltamivir; D009439:Neuraminidase