Effectiveness of Oseltamivir in Preventing Influenza in Household Contacts: A Randomized Controlled Trial

JAMA. 2001 Feb 14;285(6):748-54. doi: 10.1001/jama.285.6.748.

Abstract

Context: Influenza virus is easily spread among the household contacts of an infected person, and prevention of influenza in household contacts can control spread of influenza in the community.

Objective: To investigate the efficacy of oseltamivir in preventing spread of influenza to household contacts of influenza-infected index cases (ICs).

Design and setting: Randomized, double-blind, placebo-controlled study conducted at 76 centers in North America and Europe during the winter of 1998-1999.

Participants: Three hundred seventy-seven ICs, 163 (43%) of whom had laboratory-confirmed influenza infection, and 955 household contacts (aged >/=12 years) of all ICs (415 contacts of influenza-positive ICs).

Interventions: Household contacts were randomly assigned by household cluster to take 75 mg of oseltamivir (n = 493) or placebo (n = 462) once daily for 7 days within 48 hours of symptom onset in the IC. The ICs did not receive antiviral treatment.

Main outcome measure: Clinical influenza in contacts of influenza-positive ICs, confirmed in a laboratory by detection of virus shedding in nose and throat swabs or a 4-fold or greater increase in influenza-specific serum antibody titer between baseline and convalescent serum samples.

Results: In contacts of an influenza-positive IC, the overall protective efficacy of oseltamivir against clinical influenza was 89% for individuals (95% confidence interval [CI], 67%-97%; P<.001) and 84% for households (95% CI, 49%-95%; P<.001). In contacts of all ICs, oseltamivir also significantly reduced incidence of clinical influenza, with 89% protective efficacy (95% CI, 71%-96%; P<.001). Viral shedding was inhibited in contacts taking oseltamivir, with 84% protective efficacy (95% CI, 57%-95%; P<.001). All virus isolates from oseltamivir recipients retained sensitivity to the active metabolite. Oseltamivir was well tolerated; gastrointestinal tract effects were reported with similar frequency in oseltamivir (9.3%) and placebo (7.2%) recipients.

Conclusion: In our sample, postexposure prophylaxis with oseltamivir, 75 mg once daily for 7 days, protected close contacts of influenza-infected persons against influenza illness, prevented outbreaks within households, and was well tolerated.

Publication types

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

MeSH terms

  • Acetamides / therapeutic use*
  • Adolescent
  • Adult
  • Aged
  • Antiviral Agents / therapeutic use*
  • Double-Blind Method
  • Enzyme Inhibitors / therapeutic use*
  • Family Characteristics
  • Female
  • Humans
  • Influenza, Human / diagnosis
  • Influenza, Human / prevention & control*
  • Male
  • Middle Aged
  • Neuraminidase / antagonists & inhibitors*
  • Nose / virology
  • Orthomyxoviridae / isolation & purification
  • Oseltamivir
  • Pharynx / virology
  • Virus Shedding

Substances

  • Acetamides
  • Antiviral Agents
  • Enzyme Inhibitors
  • Oseltamivir
  • Neuraminidase