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  • The H1N1 virus that caused that pandemic is now a regular human flu virus and continues to circulate seasonally worldwide.
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CDC Health Alert Network (HAN) Info Service Message: Key Issues for Clinicians Concerning Antiviral Treatments for 2009 H1N1

Distributed via Health Alert Network
November 6, 2009, 13:51 EST (01:51 PM EST)


Although use of influenza antiviral drugs in the United States has increased during the 2009-2010 flu season, not all people recommended for antiviral treatment are getting treated. Listed below are important facts to consider when deciding whether a patient needs to be treated with antiviral medication.

It is critical to remember that it is not too late to treat, even if symptoms began more than 48 hours ago. Although antiviral treatment is most effective when begun within 48 hours of influenza illness onset, studies have shown that hospitalized patients still benefit when treatment with oseltamivir is started more than 48 hours after illness onset. Outpatients, particularly those with risk factors for severe illness who are not improving, might also benefit from treatment initiated more than 48 hours after illness onset.

Recommendations for Clinicians:

Many 2009 H1N1 patients can benefit from antiviral treatment, and all hospitalized patients with suspected or confirmed 2009 H1N1 should receive antiviral treatment with a neuraminidase inhibitor – either oseltamivir or zanamivir – as early as possible after illness onset. Moderately ill patients, especially those with risk factors for severe illness, and those who appear to be getting worse, can also benefit from treatment with neuraminidase inhibitors. A full listing of risk factors for severe influenza is available.

Although antiviral medications are recommended for treatment of 2009 H1N1 in patients with risk factors for severe disease, some people without risk factors may also benefit from antivirals. To date, 40% of children and 20% of adults hospitalized with complications of 2009 H1N1 did not have risk factors. Clinical judgment is always an essential part of treatment decisions.

When treatment of persons with suspected 2009 H1N1 influenza is indicated, it should be started empirically. If a decision is made to test for influenza, treatment should not be delayed while waiting for laboratory confirmation. The earlier antiviral treatment is given, the more effective it is for the patient. Also, rapid influenza tests often can give false negative results. If you suspect flu and feel antiviral treatment is warranted, treat even if the results of a rapid test are negative.  Obtaining more accurate testing results can take more than one day, so treatment should not be delayed while waiting for these test results. More information on influenza testing is available.

Although commercially produced pediatricoseltamivir suspension is in short supply, there are ample supplies of children's oseltamivircapsules, which can be mixed with syrup at home. In addition, pharmacies can compound adult oseltamivircapsules into a suspension for treatment of ill infants and children. Additional information on compounding is available.

For More Information

Questions & Answers:

For additional information, you can also call CDC’s toll-free hotline, 800-CDC-INFO (800-232-4636) TTY: (888) 232-6348, which is available 24 hours a day, every day.

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