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

J Am Geriatr Soc. 2001 Aug;49(8):1025-31. doi: 10.1046/j.1532-5415.2001.49204.x.


Objectives: 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.

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

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

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

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

Measurements: 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.

Conclusion: 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.

Publication types

  • Clinical Trial
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetamides / adverse effects
  • Acetamides / therapeutic use*
  • Aged
  • Aged, 80 and over
  • Antiviral Agents / adverse effects
  • Antiviral Agents / therapeutic use*
  • Double-Blind Method
  • Europe / epidemiology
  • Female
  • Frail Elderly*
  • Homes for the Aged
  • Humans
  • Influenza, Human / epidemiology
  • Influenza, Human / prevention & control*
  • Male
  • Neuraminidase / antagonists & inhibitors*
  • Oseltamivir
  • United States / epidemiology


  • Acetamides
  • Antiviral Agents
  • Oseltamivir
  • Neuraminidase