Antiviral medications for influenza.

Evidence Three 2014 systematic reviews of placebo-controlled RCTs (including > 160 000 pages of previously unreleased clinical study reports)1-3 found the following when treating otherwise healthy adults with influenza or influenzalike illness with oseltamivir (11 RCTs)1,2 or zanamivir (14 RCTs)1,3: • Time to symptom improvement was 0.6 to 0.7 days (about 10%) better1-3; the benefit of zanamivir was similar to “relief medications” (like acetaminophen).1,3 • There was no benefit for pneumonia (x-ray scan confirmed)1-3 and hospitalizations were not reported1,3 or there was no benefit.1,2 • Adverse events included the following: -For oseltamivir,1,2 the number need to harm was 28 for nausea and 22 for vomiting. -Postmarketing surveillance reports (frequency unknown) identified bronchospasm with zanamivir4 and delirium and self-injury with oseltamivir.5 A 2015 systematic review6 concluded adults receiving oseltamivir had faster symptom alleviation, and fewer lower respiratory tract complications and hospitalizations. • The review used similar studies1,2 but the conclusion was based on a subgroup with documented influenza. • The review was funded by, and 2 authors had pre-existing financial affiliations with, the manufacturer of oseltamivir. From 26 systematic reviews,7 authors with financial conflicts of interest were 5 times more likely to report benefits of NI use (this includes a systematic review of cohort studies from the 2009-2010 pandemic suggesting that NIs decreased mortality in hospitalized patients8) and less likely to report on publication bias and the quality of included studies. • Other concerns1: unpublished protocols; inconsistent outcome definition; “placebos” with potential adverse effects; and incomplete reporting (eg, missing symptom cards).