Even though the possibility of a bird flu pandemic remains unlikely, the H7N9 virus continues to infect some people in China, as treating the disease could become even more difficult.

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(ABOVE: Bird Flu Strikes China in 2013)

A new strain of the virus might be resistant to first-line flu drugs, such as Tamiflu, and could maintain its ability to spread even if a patient receives proper medication, according to a study from the Icahn School of Medicine at Mount Sinai in New York City published in the journal Nature Communications.

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An examination of three strains of the virus found that some mutations decreased susceptibility to one drug class. Researchers hypothesized that these mutations could also cause some degrees of resistance to these drugs.

Testing concluded that one mutation showed resistance to oseltamivir — marketed as Tamiflu — and did not lose any ability to replicate in humans. Unlike other flu strains, H7N9 does not become less transmissible after exposure to drugs.

Tamiflu was not the only drug unable to lessen the contagiousness of the virus. H7N9 also showed high resistance to another commonly used drug, Rapiacta, and partial resistance to Relenza.

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"Our study underscores the need to develop a bigger arsenal of antiviral drugs and vaccines, which will allow us to outsmart the influenza virus," said lead investigator Nicole Bouvier, M.D., assistant professor of medicine, infectious diseases at the Icahn School of Medicine at Mount Sinai, in a press release. “Our study suggests that flu viruses can indeed develop drug-resistant mutations without suffering a penalty in terms of their own fitness."

Additionally, testing performed on mice found that the Tamiflu did not affect the mortality or morbidity risk of the H7N9 virus.

Researchers concluded that doctors should use alternatives to Tamiflu to treat the bird flu.

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