Flu season is underway, and health officials say there are signs the vaccination may only be 10 percent effective against the main strain.

Doctors still want you to get the shot, though.

“There's very little downside to getting vaccinated and if anything that's going to be your only way to really protect yourself especially because with the holidays, the congregation of people and family getting together and things like that,” said Dr. Shivani Reddy of Kaiser Permanente. “That's how it so easily gets spread.”

Compared to this time last year, experts say there are double the number of confirmed cases of the flu.

In Ohio, 35 people have been hospitalized, but flu typically peaks in January.

Flu activity is listed as widespread in four states: Massachusetts, Georgia, Louisiana and Oklahoma.

“What we do know is that the more people who get the vaccine, the fewer people get sick, the milder the flu season is for everyone,” said Dr. John Marshall of Maimonides Medical Center.

If you’re 65 or older, there are two vaccine options designed to boost immune response. That’s important because up to a month after older adults have recovered from the flu, they’re still at an increased risk of having a heart attack or stroke.

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NBC News contributed to this report.