Neuraminidase inhibitors for influenza: a review and public health perspective in the aftermath of the 2009 pandemic.

The objectives of this study were to: (1) reflect on key stages in the discovery, development and pre-pandemic use of neuraminidase inhibitors (NAIs), (2) summarise the evidence of NAI effectiveness for treatment and prophylaxis of seasonal influenza prior to the 2009 pandemic, and (3) summarise the evidence base generated during the 2009 pandemic period. A rapid systematic review of evidence published to June 2010 was conducted where existing high-quality systematic reviews formed a baseline and were supplemented with data from other reviews, randomised controlled trials (RCTs) and observational studies. Severity and duration of symptoms; rates of severe illness, complications and death following treatment for influenza or influenza-like illness; rates of influenza and influenza-like illness following long-term prophylaxis or post-exposure prophylaxis of household contacts. Prior to the 2009 pandemic, evidence from RCTs conducted in seasonal influenza epidemics indicated that NAIs used to treat laboratory-confirmed influenza in healthy adults reduced the duration of illness by one day. NAIs provide high levels of protective efficacy in adults when given long-term or in household-based post-exposure prophylaxis for seasonal influenza. Several 2009 pandemic period observational studies suggest that early treatment may reduce rates of hospitalisation and in-hospital mortality, but data from that period do not substantially increase the evidence base on prophylaxis, although they confirm effectiveness. NAIs should be deployed during a future pandemic for either post-exposure prophylaxis or treatment depending on national policy considerations and logistics. The existing evidence base on effectiveness against severe outcomes requires supplementation.