8/18/09
The following appeared in MWMR on 8/14. It highlights the concern that many have re the possibility of Tamiflu resistance which might appear as we move forward but is, so far, not of significance.
Only sporadic cases of oseltamivir resistance associated with the H275Y mutation in the neuraminidase have been detected in immunocompetent persons exposed to oseltamivir (9). As of August 11, no evidence had been found of ongoing transmission of oseltamivir-resistant novel influenza A (H1N1) virus in the United States or elsewhere in the world. The public health risk of virus transmission from these two immunosuppressed cases with oseltamivir-resistant novel influenza A (H1N1) virus infection appears to be low. Currently, enhanced surveillance for oseltamivir resistance among novel influenza A (H1N1) virus strains isolated from outpatients and hospitalized patients is being conducted in Washington in collaboration with CDC. The two cases in immunosuppressed patients described in this report and sporadic cases of oseltamivir resistance in persons with oseltamivir exposure, highlight the need for ongoing global virologic surveillance and monitoring of antiviral resistance (10).
All circulating novel influenza A (H1N1) virus strains worldwide remain susceptible to oseltamivir and zanamivir but resistant to amantadine and rimantadine. CDC continues to recommend oseltamivir or zanamivir for treatment of all hospitalized patients with suspected or confirmed novel influenza A (H1N1) virus infection and for outpatients at increased risk for influenza-related complications (e.g., young children, pregnant women, and persons with certain chronic medical conditions) with suspected or confirmed novel influenza A (H1N1) virus infection. Novel influenza A (H1N1) virus strains with the H275Y mutation are susceptible to zanamivir. Therefore, in immunosuppressed patients with oseltamivir-resistant novel A (H1N1) virus infection, zanamivir should be considered the antiviral treatment of choice; however, zanamivir is not recommended for persons with underlying airway disease.† Additional interim guidance on the use of antiviral medications for the treatment and prevention of novel influenza A (H1N1) virus infection is available on the CDC website.