Influenza is spreading rapidly across the United States this respiratory virus season, but the Centers for Disease Control and Prevention on Friday said most Americans are not vaccinated. (Photo Credit: Tannen Maury/EPA)

Jan. 3 (UPI) -- Influenza has caused 3,100 deaths and 81,000 hospitalizations among 7.5 million flu cases so far this respiratory disease season the number of cases reported in the United States continues to rise.

The number cases is likely to continue rising for weeks as the United States enters winter and the most intense period of respiratory virus season, which, in addition to influenza, also sees strains of respiratory syncytial virus and COVID-19 increase in circulation each fall and winter, according to the Centers for Disease Control and Prevention.

Eight pediatric deaths were reported so far this flu season, including five during the week ending Dec. 20, according to the CDC.

A pediatric death is defined by the agency as the death of someone under the age of 18.

The number of flu cases rose significantly in December, but the final numbers won't be available until Monday due to the New Year holiday, CDC officials said.

The CDC advises everyone who is age 6 months and older be vaccinated against the flu and said about 130 million doses of the influenza vaccine have been distributed throughout the United States.

While the vaccine is widely available, the CDC said only 25% of adults and 17% of children received flu vaccinations before Dec. 1.

Brown University epidemiologist Jennifer Nuzzo also emphasized the importance for as many as possible to get a flu shot.

"Bottom line for people, if they haven't gotten vaccinated against the flu, they should get vaccinated, particularly young kids and older adults," Nuzzo told The Guardian.

"A lot of people are getting the flu at the same time, which is always tough," Nuzzo said.

"That is actually tougher than a situation in which people get it and it's spread out over a longer period," she explained. "It could be a worse season, in part because more people are going to need more care than hospitals can easily deliver."

Complicating the matter is a new variant, referred to as subclade k, which is spreading rapidly throughout the country, according to PBS.

The most common flu variant diagnosed so far this year is the Influenza A strain, which accounted for 96.4% of all strains diagnosed, while Influenza B accounted for 3.6% of diagnosed cases since Sept. 28.

Among the influenza A strains, H3N2 was the most prevalent, with 84.8% of those diagnosed.

The H1N1 virus, also called the swine flu, accounted for the remaining 15.2% of Influenza A strains diagnosed.

The CDC did not have information regarding the subclade k variant of Influenza A, but flu activity was rated as high or very high in 32 states and jurisdictions for the week ending Dec. 20.

That figure nearly doubles the number of states and jurisdictions rated as high or very high a week early as the annual flu season reaches its peak.

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