The purpose of this document is to provide a basis for advice to clinicians on the use of the currently available antivirals for patients presenting with illness due to influenza virus infection, as well their use for chemoprophylaxis. This guidance updates and replaces the recommendations published in August 2009. This document will again be reviewed in September 2010 and, if necessary, updated.

Key changes to the guidelines are:

• Simplification of recommendations as pandemic influenza A(H1N1) 2009 virus has become the predominant influenza virus worldwide. • Specific guidance for the treatment of young children from birth, including guidance on dose and formulation (Recommendations 06‐08). • Additional guidance for treatment or chemoprophylaxis of patients with severe immunosuppression (Recommendations 03 and 04). • Consideration of a wider range of investigational, regional1 or adjunctive treatments (Recommendations 14 and 15). • Specific contraindications for some medicines (Recommendations 16‐18)