(NEXSTAR) – Flu activity in Tennessee is very high — the highest level capable of being recorded on the Centers for Disease Control influenza map.

More than 25% of people in the U.S. who tested for flu last week were positive, according to results reported to the CDC. As of Friday, Tennessee is #2 in the country for flu activity in the Walgreen’s Flu Index.

In recent weeks, the worst flu activity has largely been in the South. But as of late November, states all over the map were in the most alarming tier.

The most common type found during testing is Influenza A(H3N2) making up 79% of cases tested last week but not all cases are subtyped. The majority of influenza viruses tested are antigenically similar to the influenza viruses included in this season’s influenza vaccine, the CDC said.

People aren’t just getting sick with the virus – many are ending up in the hospital. Nearly 20,000 people were admitted to the hospital with influenza last week. The number of flu-related hospital admissions “almost doubled” compared to the week before, the CDC said.

Only four states – Alaska, Michigan, New Hampshire and Vermont – have “low” or “minimal” activity. Two more states, Hawaii and West Virginia, have a “moderate” level of influenza infections.

CDC data shows the number of hospitalizations so far this year is already higher than any flu season since 2010-2011. Nearly 20,000 people were admitted to hospitals last week for treatment of influenza, according to the CDC.

Fourteen children have died so far this season.

Rates of influenza hospitalizations by year

The map below, updated Friday, contains data collected through the Thanksgiving week.

The CDC map isn’t based on confirmed influenza lab tests but rather tracks where people are going to the doctor with flu-like symptoms (respiratory illness and fever, plus a cough or sore throat). Because of that, the map “may capture patient visits due to other respiratory pathogens that cause similar symptoms,” the agency explains.

(Source: CDC)

While COVID-19 cases have remained pretty flat over the past several weeks, both the flu and RSV have spread widely.

Dr. Andrew Pekosz, a virologist and professor at Johns Hopkins Bloomberg School of Public Health, believes the U.S. is still in the “early stages” of a surge in influenza cases, he told Nexstar.

“For influenza, we are still on the upside of the curve, and we really have no idea what the peak number of cases will be and when that will happen,” he said.

RSV numbers may be hitting a plateau, he said, “but they’re still at a very high level. So the burden of RSV is still great, but we may be closer to the peak there than we are with flu.”

All three viral illnesses — COVID, influenza and RSV — have the potential to increase after the Thanksgiving and Christmas holidays, simply because people are getting together more often and in bigger groups.