Circulating Strains Expected for 2011-2012 Have Been Highly Susceptible to Tamiflu
Susceptibility is defined as a lack of resistance based on laboratory testing. It does not imply that use of the antiviral will have a positive effect on the clinical outcomes of any particular patient.
Influenza viruses change over time. Emergence of resistant mutations could decrease drug effectiveness. Other factors (eg, changes in viral virulence) might also diminish clinical benefit of antiviral drugs. Prescribers should consider available information on influenza drug susceptibility patterns and treatment effects when deciding whether to use Tamiflu.
Tamiflu has been studied only in strains of influenza that were circulating at the time of the pivotal trials. The magnitude of effect of Tamiflu in treating and preventing novel strains of influenza (such as those that may be involved in a pandemic) cannot be predicted.