After a tame start to the flu season, state health officials are expecting the virus to ramp up.

The state's weekly influenza update, issued Thursday, showed an increase in specimens testing positive for flu and flu-like illnesses at hospitals and clinics, though overall flu cases remain low.

"It looks like we're finally seeing an uptick, but we're nowhere near last year's rates," said Karen Martin, an epidemiologist at the Minnesota Department of Health. "Just like the rest of the country, Minnesota is seeing a late start."

Health officials speculate that a warm, wet December may have slowed the flu, which spreads better in dry weather.

In recent years, influenza often picked up in late autumn and peaked around the new year. But the timing of flu season is unpredictable, according to the U.S. Centers for Disease Control.

The last time the flu season hit late was in 2011-2012, Martin said, adding that health officials often see a second wave peak of outbreaks in the spring when the virus peaks in late autumn and early winter.

"People have short memories," Martin said. "What we're seeing this year is not out the realm of normal."

So far this year, the department has reported fewer than 100 cases that required hospitalization. In K-12 schools, the department noted 28 outbreaks.

The state is also urging health professionals to keep an eye out for flu in children and teenagers, Martin said, because they may be prone to this year's strains. The 2014-2015 flu season affected a large number of school-aged children and caused 4,153 hospitalizations. "Different influenza strains affect people differently," she said.

For people who haven't been vaccinated, Martin said flu vaccines are still abundant — and not too late. "A lot of people who wait don't think about it," she said. "People can still get vaccines, especially since we haven't hit peak yet."

State health officials recommend common disease-prevention practices, such as covering coughs, hand-washing and taking a sick day from work or school to reduce the virus' spread.

Youssef Rddad is a University of Minnesota student on assignment for the Star Tribune.