The floodgates have opened for the flu, with millions of people in the US reporting illness and nearly 3,000 deaths from the flu since early October, according to the latest statistics from the Centers for Disease Control and Prevention.

With the start of the holiday season and large family gatherings, cases are expected to continue to rise.

“We are likely to see an increase in the coming weeks,” Lynnette Brammer, an epidemiologist and leader of the CDC’s household influenza surveillance team, told NBC News.

So far this season, there have been approximately 6.2 million cases of flu, according to the most recent data from the CDC.

Twelve of the influenza deaths occurred in children.

Of the samples reported to CDC this season, about 76% are of the H3N2 strain of influenza A. The remainder are H1N1. Both versions of the flu can cause serious illness.

However, most flu patients sick enough to end up in the intensive care unit at Vanderbilt University Medical Center in Nashville have tested positive for H1N1, said Dr. Todd Rice, unit director for VUMC medical intensive care.

«People don’t have a good appreciation of how serious the flu can be,» Brammer said.

The flu appeared unusually earlier this year, along with covid and respiratory syncytial virus (RSV), which have flooded hospital systems. Several years of limited viral activity have resulted in few people with immune systems capable of fighting off the most virulent infectious diseases.

“We are dealing with three highly contagious respiratory viruses,” said Dr. Ashish Jha, coordinator of the White House Covid-19 Task Force. “Our expectation is that we will probably see an increase in the next few weeks,” particularly with influenza and covid.

However, the rise in RSV may have peaked, Jha said. «Nationwide, the numbers seem to be going down,» Jha said. «We want to see in the next two weeks where that goes. But the preliminary evidence right now is pretty hopeful.»

Why are we vulnerable?

Typical flu seasons peak in December and peak in January or February, said Dr. Julie Morita, executive vice president of the Robert Wood Johnson Foundation.

With the flu season starting early this year, many people became infected before they had a chance to get vaccinated, making it easier for the virus to spread.

“There was a larger group of people who were not vaccinated than there would have been in ordinary seasons,” said Morita, who is also a former Chicago public health commissioner. «That could be contributing to why we’re seeing such high rates of disease right now.»

As of November 28, «influenza-like illness» or ILI activity, which includes the flu, was highest in the Southeast, as well as in New York City and Washington, DC.Centers for Disease Control and Prevention

The latest CDC data on flu activity shows «very high» spread across much of the country, especially Arkansas, California, Colorado, Kentucky, Mississippi, New Mexico, South Carolina, Tennessee, Texas, Virginia , Washington and New York. City and Washington, D.C.

There is no evidence that the spread of the flu will go away anytime soon.

«It’s a pretty safe bet that flu activity will continue for several more weeks or months,» Brammer said.

Intensive care units are already seeing an increase in the sickest patients.

“Three weeks ago, we didn’t see a lot of flu in our ICU,” Rice said. «Then the floodgates opened.»

Now, between 30% and 40% of Rice’s patients who need the most intensive care have the flu.

He blames, in part, the early arrival of the flu.

“It resulted in more people being at risk because fewer people were vaccinated.”

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