Allison McGeer, MSc, MD
Is extended-duration chemoprophylaxis with neuraminidase inhibitors (NAIs) effective in preventing influenza?
Included studies compared an NAI with placebo or another NAI, given for ≥ 4 weeks, for prevention of naturally occurring influenza A virus infection. Outcomes were laboratory-confirmed symptomatic or asymptomatic influenza virus infection and adverse events.
MEDLINE, EMBASE/Excerpta Medica, BIOSIS, Cochrane Library, National Health Service Economic Evaluation, Health Technology Assessment, ACP Journal Club, Database of Abstracts of Reviews of Effectiveness, and government and drug company trial registries (to Jun 2009); and references were searched for randomized controlled trials (RCTs) that had methodological quality ≥ 3 on the 5-point Jadad scale. 7 RCTs (n = 7021, mean age 29 to 81 y, 46% to 69% women) met the selection criteria. The trials included participants at both low and high risk and those who had or had not been vaccinated against influenza. Mean Jadad score was 4; all RCTs were placebo-controlled and double-blind, and used intention-to-treat analysis. 4 RCTs evaluated oral oseltamivir, 75 mg, once or twice daily for 6 weeks, and 3 RCTs evaluated inhaled zanamivir, 10 mg, once daily for 4 weeks.
The incidence of laboratory-confirmed symptomatic influenza in the placebo groups ranged from 5.8% to 14%. NAIs reduced risk for symptomatic but not asymptomatic influenza (Table). Groups did not differ for serious adverse events overall, but risk for nausea and vomiting was increased with oseltamivir compared with placebo.
Extended-duration chemoprophylaxis with neuraminidase inhibitors is effective in preventing symptomatic influenza.
Neuraminidase inhibitors (NAIs, oseltamivir or zanamivir) vs placebo for prevention of seasonal influenza*
*Abbreviations defined in Glossary. Weighted event rates, RRR, RRI, NNT, NNH, and CI calculated from data in article using a random-effects model.
McGeer A. Review: Extended-duration chemoprophylaxis with neuraminidase inhibitors prevents symptomatic influenza. Ann Intern Med. ;152:JC3–3. doi: 10.7326/0003-4819-152-6-201003160-02003
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Published: Ann Intern Med. 2010;152(6):JC3-3.
Infectious Disease, Influenza.
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