Context

The neuraminidase inhibitor zanamivir, administered as an inhaled powder, is approved for the prevention and treatment of influenza in adults and children older than 7 years. Previous systematic reviews (SRs) of zanamivir may have been affected by publication bias and missing data, and clinical recommendations based on such studies should be considered inadequate.1 ,2 To deal with these shortcomings, this SR and meta-analysis (an update of a Cochrane Review)3 reanalysed the prophylactic and treatment effects of zanamivir on those suffering from influenza, based on the full clinical study reports of all relevant trials provided by the manufacturer and on regulatory comments.