A sudden spike in flu cases over the holidays is filling emergency rooms and urgent care centers across the state and has health officials fearing this could be one of the worst influenza seasons in years.

More than 120 Minnesotans were hospitalized with the flu in the week that ended Dec. 22 -- nearly twice the number of the previous week and more than a third of the total so far this year. The number of cases confirmed by laboratory testing also surged during the same week, reaching peaks reported much later in the previous two flu seasons. Yet it's still early, said Kris Ehresmann, director of infectious disease at the Minnesota Department of Health.

"That suggests this has the potential to be severe," she said.

Since Dec. 22, the number of ill people showing up at emergency rooms and clinics has continued unabated, say health officials. And some say it's just as bad as it was at the same time of year during the 2009 H1N1 pandemic when 1,800 people in Minnesota were hospitalized over a 12-month period. Since the official start of the flu season in October, 297 people have been hospitalized. The Health Department will release updated numbers later this week.

"It's the highest number of patients with flu since H1N1," said Dr. Brent Asplin, chief clinical officer for Fairview Health Services. "Over the weekend all our community hospitals were at or near capacity."

Hospital emergency rooms and urgent care centers are especially busy, hospital officials said, and though the number of infected people who have to be hospitalized is small relative to the number who are ill, some hospitals are scrambling.

The Mayo Clinic's hospital in Mankato now has 15 patients with the flu, said Kevin Burns, director of public affairs for Mayo Health System. They are all in one unit, in part to control the spread of infection, which is standard procedure, he said.

"But what is unusual is the timing," he said. "It's quite a bit earlier than we would normally see."

Hitting across age groups

Patients are spanning the age range, from children to the elderly, officials said.

So far, hospitals have been able to handle the extra cases. But some have added staffed beds to accommodate the extra demand, and the Health Department is tracking the availability on a daily basis.

"A number of hospitals are at very high capacity," said Jane Braun, director of emergency preparedness for the Health Department. "No one is turning patients away, but some are adding extras wings and using those types of strategies to absorb additional demand."

But at a number of hospitals, staff members are also coming down with the virus, adding to the pressure.

"We are seeing high numbers of sick calls for both staff and their kids," said Asplin. "But it's important that they stay home from work or school."

This year's most common strain, H3N2, is also causing more severe symptoms than normal, said Ehresmann, and that could be contributing to the number of people showing up in emergency rooms and urgent care centers reporting fever, fatigue and a cough.

"A number do look quite ill," said Dr. Danielle Hart, a physician in Hennepin County Medical Center's emergency department.

Treatment for some

But doctors said that only children under 2, the elderly, people with underlying health conditions such as diabetes or heart failure, or those who live with those people should seek anti-viral medication from a physician. Otherwise-healthy people who don't live with someone at risk would not be treated, Asplin said. Their best option is to stay home, rest and take over-the-counter medications to control their symptoms, he said.

Health officials said the flu vaccine, which is widely available, is the best insurance against infection. It will protect about 60 percent of the otherwise-healthy adults, Ehresmann said. And though that's not perfect, she said, without vaccination "it's zero."

Josephine Marcotty • 612-673-7394