What to know about new subclade K strain of the influenza

A rapidly spreading strain of influenza known as subclade K is dominant in Arizona and the U.S., but there’s no current evidence that it’s causing more severe illness.

The strain is referred to as a “super flu” in some headlines and social media posts. It’s true the strain is causing a rise in flu cases, but David Engelthaler, who leads the infectious-diseases division of the Arizona-based Translational Genomics Research Institute, called that a stretch.