MINNEAPOLIS (WCCO) – The flu remains widespread across Minnesota.

And now that kids are returning to school this week, there’s concern we’ll see another spike in the number of cases. The highest number of flu cases are typically seen in January, after the holidays.

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But even if you’ve already had the flu, you’re not immune from getting it again.

Patsy Stinchfield is the director of infection prevention and control at Children’s Hospitals and Clinics.

“The number of kids we saw in the month of December–we have never seen like this ever before,” she said. “I have been here 27 years and this was really record-breaking.”

Typically during the month of December, the staff at Children’s Hospitals and Clinics see 18 positive tests for influenza.

In 2013 they were surprised when that number jumped to 292.

But then, this past month, 707 kids tested positive for the flu.

“A lot of people think ‘just the flu,’ and we want to take those words apart, because flu is a very serious virus,” she said.

She said about 100 children had such severe flu symptoms they had to be admitted.

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Twenty-five of those ended up in the intensive care unit. Most of them had not had a flu shot.

“Our experience here at Children’s really shows that those kids who get the flu vaccine–even though there is a mismatch this year–are kept out of the ICU, are kept out of hospitalization more than kids who are un-vaccinated,” she said.

Even if you’ve already had the flu this winter, there is still a chance you could get it again.

That’s because there are several different strains of the flu.

“If you have already had the H3 strain of the flu, you have gotten some good immunity,” she said. “However, later in the spring, sometimes a different strain can emerge, the B-strain of influenza.”

Stinchfield said that typically it’s late in the flu season–in March, April, May–when we see those additional strains of the flu pop up, and people can get sick a second time.

“It is not too late to vaccinate,” she said. “We really think that it is a wise idea.”

The flu vaccine is recommended because it will reduce the severity of your symptoms.

It’s difficult to protect yourself from family members with the flu, because people are contagious about two days before they start showing any symptoms. During that time, everyone in the house is vulnerable to the surfaces where they may have left germs.

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Some prevention tips are to use paper towels rather than hand towels in the bathroom and kitchen and to wash your hands frequently.