FILE - In this Wednesday, Feb. 7, 2018 file photo, a nurse prepares a flu shot at the Salvation Army in Atlanta. The U.S. government's Friday, Feb. 9, 2018 flu report showed the flu has further tightened its grip on the U.S. This season is now as intense as the swine flu epidemic nine years ago. (Associated Press/The Minnesota Star Tribune)

Minnesota has recorded three new child flu deaths and an uptick in school outbreaks, signs that the state's influenza season is catching up to the nation's in severity.

The number of Minnesotans hospitalized with flu symptoms also has set a record — nearly 4,300 — the highest since the Minnesota Health Department began tracking them in 2008.

"It is a severe season," said Karen Martin, a state epidemiologist who tracks the flu. "We are hopeful that we are beginning to see the downward trend start, but we are still at very high activity."

The numbers, released Thursday in the department's weekly flu update, came as the U.S. Centers for Disease Control and Prevention reported that this year's flu vaccine is 36 percent effective overall but only 25 percent effective against this season's most dominant and virulent strain, H3N2.

The vaccine's efficacy rate since 2004 has varied from a low of 10 percent to a high of 60 percent. Vaccines vary in effectiveness from one year to another because different strains of influenza circulate each year. Some strains are more resistant to vaccines than others, and vaccine manufacturers have to make their best guess months before the season peaks.

Still, health officials encourage people to get a flu shot because it provides some protection and can help moderate symptoms for those who catch the virus.

"For anyone, it is still worthwhile to get vaccinated. But particularly in light that we are seeing more pediatric influenza deaths, we really encourage parents to get their kids vaccinated," said Martin.

In fact, the CDC reported Thursday that the flu vaccine is providing more protection — with 59 percent effectiveness — for children age 6 months to 8 years.

A total of four child deaths in Minnesota have now been reported for this season. Health officials said they could not disclose details about any of those cases.

Nationwide, there have been at least 63 pediatric flu-related deaths since Oct. 1. Most children who die from the flu had not been vaccinated, according to a CDC study.

Minnesota schools continue to get hit with outbreaks that are far outpacing last season. Cases surged after students returned from the winter holiday break. Although the number of school outbreaks has fallen since the third week of January, there were still 108 last week and 102 in the previous week, for a total of 525 this season.

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While the number of outbreaks has been high, some of the larger metro school districts said Thursday that illnesses have not had a major impact on school operations.

"We have not seen that in our district to the point where there might be hundreds of students missing from school," said James Skelly, spokesman for the Anoka-Hennepin School District.

Nonetheless, school nurses continue to provide students and parents with basic health information, just as they do throughout the school year. "We are always promoting immunizations," said Amber Spaniol, director of nursing services at Minneapolis Public Schools.

As part of winter wellness education, the district is encouraging hand-washing and advising parents about when kids should stay home from school and when to return after illness.

The state's nursing homes and other long-term care facilities have also felt the impact, with 150 cases this season, including 12 last week. Martin said that nearly half of the state's skilled nursing facilities have reported an influenza outbreak this season.

Medical clinics reported that 5.3 percent of all patients were coming in with flu-like symptoms, which include fever, chills, muscle aches, cough, congestion, runny nose, headaches and fatigue.

Hospitalizations fell about 50 percent last week, to 255, but that number could increase as facilities continue to report new cases to the Health Department. With a total of 4,271 hospitalizations this season, Minnesota has eclipsed the previous high, 4,138, in the 2014-2015 flu season.

"The fact that it is still February and we have passed those numbers is significant," Martin said.

Flu season can last into May.

Toward the end of any flu season, Minnesota typically sees an increase in the number of cases that are known as B-type flu strains. Depending on how those strains spread, the state could see a new resurgence of flu infections. "For the past few weeks, several indicators have gone down," said Martin. "It is hard to say whether we have completely peaked."

Glenn Howatt • 612-673-7192