Flu in Minnesota continued its march across the state during the holidays, holding firm at a level considered widespread, according to the weekly report published Wednesday by the Minnesota Department of Health.

Hospitalizations for flu increased to a total of 577, compared with the 380 reported in the week of Dec. 24, maintaining the pace set during the brutal 2009-10 influenza pandemic, health officials said.

"At this point flu is continuing with vigorous activity," said Kris Ehresmann, director of epidemiology for the state health department. "We've had almost 200 more hospitalizations since last week."

Minnesota has had severe flu levels since early December, and only now is the rest of the country catching up. On Tuesday, the Centers for Disease Control and Prevention declared that it has reached epidemic levels across the country, with 22 states reporting high levels of activity and 15 pediatric deaths. Three of those were in Minnesota.

"I've never seen a December like this," said Patsy Stinchfield, director of infection control and prevention at Children's Hospitals and Clinics. Its clinics have 748 lab-confirmed cases of flu and close to 100 children have been hospitalized there.

In its report Wednesday, the state health department said 30 percent of the medical specimens sent in for testing from 310 surveillance clinics around the state were positive for influenza virus, a slight increase over the previous week. The number of school outbreaks were down largely because schools were not in session because of the holidays, Ehresmann said. Still, there were 34 reported outbreaks compared with 315 the previous week, a new weekly record. The previous high of 288 school outbreaks was set during the 2009-10 pandemic. Since October 2014, 622 schools have reported outbreaks.

There were 22 outbreaks in long-term care facilities compared with 33 the previous week.

This year's dominant flu strain is H3, one that historically has been hardest on the elderly and on very young children. Compounding the problem is that the vaccine is not a good match to the virus circulating this year. Health experts, however, say it still does provide some protection and are encouraging vaccination as a way of mitigating the spread and severity of the infection.

Stinchfield said most of the 24 kids with flu who were treated in Children's intensive care unit had not been vaccinated. It's an indication, she said, that the vaccine does provide protection.

Other emergency rooms continue to be busier than normal as well, hospital officials said.

"We are seeing a lot of upper respiratory illness," said Mary Ellen Bennett, director of infection prevention at Hennepin County Medical Center. "There are a lot of things out there."

Children's Hospitals and Clinics said it has had 689 admissions in December alone, record-breaking numbers for this early in the season. This is likely lower than the actual number of flu cases as many kids don't get tested who have influenza.

Earlier in December some hospitals were reporting record volumes of patients, and some had to briefly close their emergency rooms and divert ambulances to other hospitals.

Ehresmann said in addition to getting the vaccine, the best defense is regular hand-washing to stop the spread of the virus, rest and staying home when you're sick.

"That all makes a huge difference," she said.