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TDSHS information regarding flu resistance to Oseltamivir

Jan 15, 2014
From Texas Department of State Health Services

Information Regarding Resistance to the Neuraminidase Inhibitor Oseltamivir

 This flu season, 910 2009 H1N1 virus samples nationally have been tested for resistance to the neuraminidase inhibitor oseltamivir. While the majority of the tested viruses show susceptibility to oseltamivir, 10 (1.1%) were resistant to oseltamivir. Of the 2009 H1N1 virus samples tested for resistance to the neuraminidase inhibitor zanamivir, none was resistant.

Texas is now one of the states that has oseltamivir-resistant 2009 H1N1 virus detected. While the DSHS and CDC flu reports will not be updated with this information until next week, DSHS wants clinicians to be aware.

The CDC guidance for antiviral drug treatment is pending review for the 2013-2014 influenza season. However, intravenous zanamivir is currently still the recommended antiviral treatment for severely ill patients with highly suspected or confirmed oseltamivir-resistant 2009 H1N1 virus infection. Peramivir is not available for compassionate use or via Emergency Use Authorization (EUA) at this time.

Please continue to encourage vaccination for everyone who is at least 6 months of age.

When there is a clinical suspicion of influenza and antiviral treatment is indicated, antiviral treatment with oseltamivir or zanamivir should be started as soon as possible. Decisions about starting antiviral treatment should not wait for laboratory confirmation of influenza.

Please see the CDC website for additional influenza-related information.

Lesley Brannan, MPH
Epidemiologist / State Influenza Surveillance Coordinator
Emerging and Acute Infectious DiseaseBranch
Texas Department of State Health Services
(512) 776-6354