CDC identifies drug-resistant flu variant in the U.S.

The CDC has identified a new dual-mutant strain of the flu virus that has been drug resistant to the most commonly used antiviral drugs - Photo by UnSplash +

Two cases have been identified so far

As bird flu continues to make headlines, the more common variant of influenza hasn’t garnered as much attention as of late. 

However, according to a new study from the Centers for Disease Control and Prevention (CDC), two cases of a drug-resistant flu variant have been identified in the United States. 

The new strain is being dubbed a “dual-mutant” variant, which combines two strains of the flu virus – I233V and S247N – into one. In both instances, the variant was resistant to typical antiviral treatments. 

Where did it start?

While this new strain of the flu virus was first identified earlier this year in Hong Kong, the CDC regularly monitors variations of the influenza virus. Between May 2023 and February 2024, the organization analyzed over 2,000 viral strains from the U.S. and around the world. 

Over 100 of the samples tested turned out to be this dual-mutant strain, and the infected samples came from over a dozen countries. Most recently, this strain was detected in Europe in February of this year. 

“Analysis of available sequence data revealed that dual mutants have been in global circulation since May 2023; overall detection frequency was low,” the CDC wrote in its report. “However, those data may not necessarily represent the actual proportion of what was in circulation because of differences in surveillance and sequencing strategies in each country.” 

In other words, the numbers show that this dual-mutant strain wasn’t nearly as prevalent as other strains of the flu virus; however, consumers also need to consider that not every country monitors the flu the same, so it remains something to be mindful of. 

What does this mean? 

Further testing of the dual-mutant variant showed that it was 16 times less susceptible to Tamiflu, the name-brand antiviral most commonly used to improve flu symptoms. 

According to the CDC, getting your flu vaccine annually is still the best means of protection against the virus. The flu vaccine is likely to reduce the severity of symptoms, and lower consumers’ risk of hospitalization and death. 

In terms of this dual-mutant variant, the organization plans to continue monitoring the situation. 

“Our study highlights the need to closely monitor evaluation of dual mutants because additional changes may further affect susceptibility to antiviral drugs or provide a competitive advantage over circulating wild-type viruses,” the CDC wrote. 

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