According to New York state, Nassau and Suffolk flu cases more than doubled at the end of November.

Nearly 18,000 cases have been reported across New York by the state's Health Department.

Flu cases increased 114% in the state in the past week.

"Every day we're doing testing here in the office, and we're finding more and more kids coming in with flu-like illnesses, and we're testing them and they're positive for flu," said East Meadow-based pediatrician Dr. John Zaso.

Dr. Zaso says the current flu hitting Long Island has evolved and is able to evade our immune system better, making this strain more aggressive.

"Every person should get the flu shot, there's no reason not to get it. It's safe, it's effective, Dr. Zaso said.

He says it is hitting everyone from kids, to seniors, to healthy adults.

Dr. Zaso says it takes about two weeks for the vaccine to produce immunity. He says after getting the flu shot it's still possible to get the flu, but the shot can prevent a serious complication from the illness.

"People who are healthy, otherwise well, can get pneumonia, encephalitis, they can end up with myocarditis, infection of the heart, from the flu," he said.

Shawn O'Shea, from Levittown, says he got his flu shot, knowing how bad it can be to catch the virus.

"I had it years ago real bad, and you're bedridden," says the 85-year-old.

Doctors recommend anyone six months and older get a flu shot.