Effectiveness of Oseltamivir in Preventing Influenza in Household Contacts<SUBTITLE>A Randomized Controlled Trial</SUBTITLE>

Abstract

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.

Risk factors of influenza transmission in households

“…It has been reported that 75-80% of household transmissions occur directly from the influenza-positive index patient or from the same source of infection as the index patient. 7,8 In this group, all of the clinical secondary cases have an influenza aetiology. The remaining 20-25% are due to transmission from the community at large.…”

“…This definition is based on the criteria that define influenza-like illness in clinical trials of neuraminidase inhibitors. 7,8,13 Household contacts who developed clinical influenza within 5 days of the initial visit of the index patient were classified as secondary patients.…”

“…These figures are within the range of previously published estimates in comparable placebo groups of clinical trials. 5,7,8 Overall, although we do not know the exact proportion of patients with influenza among the contacts showing symptoms of clinical influenza, we can provide an estimate. It has been reported that 75-80% of household transmissions occur directly from the influenza-positive index patient or from the same source of infection as the index patient.…”

“…[6][7][8] However, no data are available on the quantitative evaluation of the predictors of influenza transmission in households.…”

Existing Influenza Antivirals: Their Mechanisms of Action and Potential in the Face of Avian Influenza

“…39 Also, post -exposure prophylaxis with oseltamivir, 75 mg once daily for 7 days, was found to protect close contacts of infl uenza -infected persons against infl uenza illness and prevented spread within households. 40 Post -exposure prophylaxis with oseltamivir can be considered an effective option for preventing the transmission of infl uenza within households. 41 It should be recognized, however, that oseltamivir is less effective against infl uenza B than against infl uenza A -that is, with regard to duration of fever and virus persistence.…”