A new flu strain is spreading abroad. What that means for the US.

A new variant of influenza H3N2 is spreading in other countries. But that could mean the U.S. is in for a rough flu season.

The mutated strain, known as subclade K, is causing a surge in cases in the United Kingdom, Canada, and Japan.

While H1N1 predominated flu season this year in the Southern Hemisphere, with the H3N2 subclade K taking off only at the end, early data from the UK and Japan show H3N2 subclade K was represented in 90% of flu samples, the University of Minnesota wrote in a report earlier this month.