[citation needed] In October 2009, it was reported that the experimental antiviral drug peramivir had been "life-saving" effective in intravenous treating 8 serious cases of swine flu.

[5] On October 23, the U.S. Food and Drug Administration (FDA) issued an Emergency Use Authorization for peramivir, allowing the use of the drug in intravenous form for hospitalized patients only in cases where the other available methods of treatment are ineffective or unavailable;[6] for instance, if oseltamivir resistance develops and a person is unable to take zanamivir via the inhaled route.

The U.S. government (department of Health and Human Services) gave BioCryst Pharmaceuticals more than $77 million to finish the Phase III clinical development of peramivir.

[10] In 2013 the Biomedical Advanced Research and Development Authority (BARDA/HHS) released new funding under the current $234.8 million contract to enable completion of a New Drug Application filing for intravenous (IV) peramivir.

[11] According to a research report published in June 2011, a new variant of swine flu had emerged in Asia with a genetic adaptation (a S247N neuraminidase mutation) giving some resistance to oseltamivir and zanamivir, but no significant reduction in sensitivity to peramivir.