(CNN) — The latest data on respiratory illness in the United States shows that shoppers and merry-makers are spreading more than just holiday cheer: They’re also passing around germs. In many cases, it’s a new virus variant that’s been causing early and busy flu seasons in Asia, Australia and Europe.

The US is on the cusp of finding out what this flu variant, called subclade K, will do. For the week ending December 6 — the first full week after the Thanksgiving holiday — the proportion of doctor’s visits for symptoms including fever plus a cough or sore throat rose to 3.2%, according to the US Centers for Disease Control and Prevention.

That’s above a national baseline that infectious disease experts call the epidemic threshold. It’s a signal that flu season is officially underway, said

See Full Page