Minnesota reported its first pediatric death of the 2014-2015 flu season Thursday, along with several new outbreaks across the state, even as federal health officials warned that the current vaccine might be less effective than in some other years.

The victim was under 18, but was not otherwise identified by the Minnesota Department of Health. In its weekly update on the virus, the department said 18 Minnesotans were hospitalized with flu symptoms last week, about average for this stage of flu season, and eight school districts reported new outbreaks.

Mindful of comments Thursday morning by the U.S. Centers for Disease Control and Preventions (CDC), state health officials also issued a new advisory to Minnesota doctors and clinics, urging them to encourage patients to get flu shots. Even if the vaccine is only 50 to 60 percent effective, department officials noted, that's better than zero protection.

During a briefing Thursday, CDC Director Dr. Tom Frieden predicted that this year's flu season could be worse than average. One reason is that the current vaccine does not protect well against one strain, a variant of H3N2, that is particularly virulent — resulting in more hospitalizations and deaths in previous flu seasons — and has emerged as this year's dominant strain.

"Though we cannot predict what will happen the rest of this flu season, it's possible we may have a season that's more severe than most," he said.

Influenza's severity varies widely from one year to the next, with a shifting composition of flu strains and their effects. The national death toll has ranged from 3,000 to 49,000 annually in recent years, the CDC said.

CDC officials think the vaccine should provide some protection and still are urging people to get vaccinated. But it probably won't be as good as if the vaccine strain was a match.

Flu season typically begins in late fall and peaks between December and February.

Symptoms include fever, sore throat, cough and body aches. Most patients recover within a few days, but the virus can produce serious complications in vulnerable patients, especially children, the elderly and people with underlying health conditions such as asthma and diabetes.

CDC officials said doctors should be on the lookout for patients who may be at higher risk for flu complications. Such patients should be seen promptly, and perhaps treated immediately with antiviral medications, the CDC advised. If a patient is very sick or at high risk, a doctor shouldn't wait for a positive flu test result to prescribe the drugs — especially this year, CDC officials said.

The medicines are most effective if taken within two days of the onset of symptoms. They won't immediately cure the illness, but can lessen its severity and shorten suffering by about a day, Frieden said.

He was echoed by Dr. Richard Zimmerman, a University of Pittsburgh flu vaccine researcher. Some doctors may hesitate, reasoning that flu season usually doesn't hit hard until around February. But it appears to have arrived in many parts of the country already and "it's time to use them," Zimmerman said.

Nearly 150 million doses of flu vaccine have been distributed for this flu season.

Current flu vaccines are built to protect against three or four different kinds of flu virus. The ingredients always include a Type A H3N2 flu virus. The most severe flu seasons tend to be dominated by some version of that kind of flu bug. In March, after the vaccine production was underway, health officials noted the appearance of a new and different strain of H3N2. "This is not something that's been around before," Frieden said.