Flu seasons have been particularly severe in recent years and this one in no different.
An estimated 6.2 million to 7.3 million people in the United States have been sick with the flu since October, federal health officials said Friday. At least half of those people have sought medical care for their illness and 69,000 to 84,000 people have been hospitalized during the Oct. 1 to Jan. 5 period, the Centers for Disease Control and Prevention estimated.
This is the first time the CDC has provided such flu estimates for the 2018-2019 season. The estimates are extrapolated from data from about 27 million people, or about 8.5 percent of the U.S. population, federal health officials said.
The CDC wouldn't provide data on how many people have died from flu-like illness so far this season, adding it will do so once "there is sufficient data to support a more precise estimate for that outcome."
The flu season typically runs from October to as late as May, with activity tending to peak between December and February, according to the CDC. The agency recommends getting vaccinated early, ideally by the end of October, before the flu starts spreading.
Babies older than 6 months should get vaccinated with a traditional shot. For toddlers age 2 or older a shot or a nasal spray called FluMist is recommended.
The CDC also recommends that people with a flu-like illness should stay home for at least 24 hours after the fever is gone except to get medical care or for other necessities.
Thirty-seven percent of U.S. adults were estimated to have been vaccinated last flu season, down 6 percentage points from the previous year, according to the CDC. It estimates that the flu killed more than 80,000 people and caused more than 900,000 hospitalizations last year.
—CNBC's Angelica LaVito contributed to this report.