Reported cases of the flu are on the rise, but doctors say this year's flu vaccine may not fully protect you.
There's a slight variation in the virus that's now circulating, making the vaccine less effective.
The CDC says it is too late to make a new vaccine for this flu season. It would take four months to create one, to better protect against the virus that has mutated since the current flu shots were made.
"I would rather be hit by a truck than to have the flu again, it was bad," said Greg Ward of Oklahoma City, who had the flu 20 years ago.
Since then, he's gotten the flu vaccine every year, including this October. But, he recently got word from his doctor that the shot may not be enough.
"I got an email stating of my original inoculation, I needed to come back and get a second one of the same dose," Ward said,
It's a strain of Influenza A virus H3N2 that's changed from what doctors predicted this season.
"So it's not as good as a match to the vaccine as it may have been if it hadn't slightly changed," said epidemiologist Kendra Dougherty of the Oklahoma State Department of Health.
That slight change has made the vaccine about 50 percent effective.
This type of H3N2 strain tends to be more severe in young children, the elderly and pregnant women. People with chronic conditions like asthma and heart disease are also at high risk.
The Oklahoma State Department of Health reports 18 people have been hospitalized in the last week with the flu, and a total of 52 people have been hospitalized so far this flu season.
Doctors still urge getting the flu shot.
"Even though the H3 component of the vaccine may not protect them 100 percent, it still could offer them some protection," Dougherty said.
If you already got the vaccine, doctors say getting a second shot isn't necessary. Patients can take antiviral medications like Tamiflu as soon as symptoms develop.
But Ward says he's not taking any chances.
“I know it's tough for a lot of people to recover from it if at all sometimes,” Ward said.
"So they've impressed upon me that at my age, and with diabetes it's better for me to get it than to not."
Doctors say this year's flu vaccine does protect from the H1N1 virus and Influenza B, which is a strain that they're seeing some cases of in Oklahoma.
Dougherty said even though flu cases have increased in Oklahoma, the numbers are about the same as last year.