It feels like the flu, looks like the flu, but is it actually the flu?

It may not be.

There's a new virus out there making news that includes symptoms eerily similar to the flu, but it's not getting tested for regularly by doctors. It's called adenovirus, and we talked to doctors to see if you should be worried about it.

So what is the adenovirus?

It was discovered in the 1950s and has a lot of the same nastiness as the flu – runny nose, sore throat, cough, headache and, like the flu, it can cause upper respiratory infections, pneumonia and bronchitis if not treated.

However, the virus is pretty rare, and they've already developed a vaccine to fight against two strains of it, which they're using for the military.

And while it's a serious illness, the good news is that most of the infections are what medical professionals call "self-limiting."

"You get better with time," said 11Alive medical correspondent Dr. Sujatha Reddy. "Most infections with adenovirus are just going to get better on their own, so it's just grandma's chicken soup and rest is all you should need."

Contributing: Dr. Sujatha Reddy