During the past week, flu activity in the United States has increased, federal health officials say, with nine of 10 regions in the country reporting increases.

In all, 29 states are reporting flu activity, with high levels of flu in 12 states, the U.S. Centers for Disease Control and Prevention (CDC) said on Friday. Moderate activity is being seen in New York City and five states, and 33 states are seeing low or minimal activity, the agency said.

"Today's report confirms that the U.S. flu season is off to an early start," CDC Director Dr. Thomas Frieden said in an agency news release.

"It's too early to tell how severe our season might be. However, we know that thousands die and hundreds of thousands of people are hospitalized with flu each year," Frieden said. "Vaccination is the single most important step we can take to protect ourselves and our families against infection. It's not too late to get vaccinated before the flu season peaks."

According to the CDC's FluView report, states now reporting high levels of flu include: Alabama, Georgia, Illinois, Louisiana, Mississippi, Missouri, North Carolina, South Carolina, Tennessee, Texas, Utah and Virginia.

Flu season usually peaks in mid-February, but can last into the spring. The CDC advises that everyone six months and older get vaccinated.

Previously, the agency said this year's vaccine is an "excellent" match for the strains of the flu virus circulating.

People at particular risk for flu and its complications, such as pregnant women, those aged 65 and older, and anyone with a chronic illness, are urged to get their shot, the CDC said.

So far, deaths attributable to flu have remained below what the CDC considers an epidemic level. Two children, however, have died from complications from the flu, the agency noted.