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J Am Geriatr Soc. 2001 Aug;49(8):1025-31.

Long-term use of oseltamivir for the prophylaxis of influenza in a vaccinated frail older population.

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Protocare Trials at the San Antonio Center for Clinical Research, San Antonio, Texas, USA.

Erratum in

  • J Am Geriatr Soc. 2013 Mar;61(3):478.



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.


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


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


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


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


The primary efficacy endpoint was laboratory-confirmed clinical influenza.


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.


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.

[Indexed for MEDLINE]

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