A. Martinez

And remember, the flu can be deadly.

There have already been more than 3,000 deaths this season.

Lisa Groskopf is a medical officer at the CDC.

Experts say the virus is moving and they expect the entire country to see high case counts soon.

So what's driving this surge?

Well, one big factor is a new strain called subclade K. It's caused a huge number of cases from Australia to Japan to the UK.

Here is Florian Kramer of the Eichen School of Medicine at Mount Sinai in New York.

The good news is it doesn't seem to be more severe or dangerous and our treatments still work against it.

But the genetic changes in the virus mean the flu vaccine this year is a bit of a mismatch.

That's because the vaccine had already been formulated before this strain emerged.

However, early data from the UK suggests that the vaccine is still quite effective at keeping people from getting so sick they end up in the hospital.

Yes.

Both people outside and inside the agency have told me that the quality of the data looks good.

But some have raised concerns about the lack of a strong flu vaccination campaign from the federal government.

Here's Andrew Pekosz of Johns Hopkins University.

Adult flu vaccination rates are just above 40%.

That number's been trending down for several years.

The CDC's Grosskopf told me getting vaccinated was one of the most important things you can do.

But I should add, I got a follow-up email from a different CDC spokesperson saying vaccines are a personal choice and that people should speak to their health care providers about the risks and benefits.

All the basic precautions like hand washing and masking do work, and it's good to remember there are antiviral treatments, and they work best if you get them early, within the first two days of symptoms.