(USA TODAY) -- The current flu season is hitting the nation with deadly force, so far killing 18 children and sending people in 29 states to medical clinics and hospitals.

Government health experts say the flu is worse than normal, starting earlier and covering a broader region of the country. More than 2,200 people were hospitalized with flu symptoms through the end of 2012.

"It has been relatively widespread across the United States," said Trish Perl, an epidemiologist for the Johns Hopkins Health System in Baltimore and a co-leader of a flu study involving about 100 clinics in several cities.

For the fourth week in a row, the proportion of people seeing health care providers for a flulike illness is above normal, jumping from 2.8% to 5.6% in that time, the Centers for Disease Control and Prevention in Atlanta says. Last season's proportion peaked at 2.2%, the CDC reports.

The 29 states affected, plus New York City, are now reporting high flulike activity, up from 16 states the week before, the CDC says.

The public should be concerned, says Gregory Poland, professor of medicine and infectious disease at the Mayo Clinic in Rochester, Minn.

"We have this cultural thing in the U.S. about, 'Oh, it's just the flu,'" said Poland, who directs Mayo's Vaccine Research Group. "A decade ago, when we had widespread circulation (of the seasonal flu), we had 70,000 deaths in the U.S."

The medical industry is worried because this is the earliest flu season the country has seen in the past 10 to 12 years, says Michael Jhung, an epidemiologist and influenza expert at the CDC.

Flu season typically peaks in January and February, according to Flu.gov, maintained by the Department of Health and Human Services.

The predominant type of flu circulating is H3N2 Influenza A virus, making up 76% of the cases reported, according to the CDC. H3N2 flu seasons tend to be more severe.

The outbreak has strongly affected the East and the South and is spreading westward, Poland says.

Perl reports that initially health professionals were seeing a lot of Influenza B, but now they are seeing mostly A as well as other respiratory illnesses, including respiratory syncytial virus, or RSV.

The outbreak has sent thousands of people to doctors and hospitals with flu symptoms.

For instance, in Minnesota, 600 people were hospitalized from the flu and four people died, Poland says.

Among those who died was an otherwise healthy 17-year-old boy who was visiting the Twin Cities area from Texas, Poland said.

"It's not too late to get vaccinated, and the CDC encourages everyone who hasn't been to do so soon," Jhung says.

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