Flu has sickened between 6 and 7 million people in the United States so far this season, sending about half to the doctor for fever, chills and other influenza symptoms, according to estimates released Friday by federal health officials.

Of those who sought medical care, between 69,000 and 84,000 people have been hospitalized, according to a report from the Centers for Disease Control and Prevention. Agency officials are providing the estimates for the first time during flu season to underscore the risks of serious complications of the respiratory virus and to encourage people to get vaccinated. In the past, the CDC provided these estimates at the end of each flu season.

“We decided that this year, we would try to release these preliminary numbers of illnesses each week so that we could give people a better picture,” said Alicia Fry, who heads the CDC’s epidemiology and prevention branch in the influenza division. The CDC releases a report each week on seasonal influenza in the United States, along with detailed graphs and charts. But until Friday, the reports did not provide data on how many people have gotten sick, gone to the doctor, been hospitalized or died. The agency released that information at the end of each season after analyzing the data.

The preliminary figures released Friday don’t include estimates of flu-related deaths, which officials said will be provided at a later time, when there is sufficient data to support a more precise estimate.

CDC officials hope these estimates, which they plan to update weekly, will help get out their public health message.

Flu season is not over, and it’s not too late to get vaccinated, Fry said. A flu shot can prevent infections and also reduce the severity of complications, including death, from the disease. Even if someone gets sick with flu, antiviral drugs may be an option, she said, especially for people who are at high risk of serious flu complications, including young children, adults 65 and older, pregnant women and people with certain medical conditions such as asthma, diabetes and heart disease.

Antiviral drugs can lessen symptoms and shorten the time someone is sick by a day or two, clinicians say. They can also prevent complications such as pneumonia.

“We’re well into the flu season,” Fry said. Flu is widespread in 30 states, according to the latest data, and the season is expected to last for several more weeks. It’s too early to know how bad the 2018-2019 flu season will be. “But it does not look anywhere as severe as last year,” she said.

Still, people should not assume that they don’t need a flu shot, because influenza can cause serious illness each season, she said.

During the previous flu season, the virus killed and hospitalized more people in the United States than any seasonal influenza in decades. The CDC estimated that flu sickened 49 million people, hospitalized 960,000 and killed about 80,000 people. The previous high for a regular flu season, based on analyses dating back more than three decades, was 56,000. It also killed 185 children last season, a record for seasonal influenza. So far this season, 16 pediatric deaths have been reported to the CDC. The figure doesn’t include the immigrant boy from Guatemala who tested positive for influenza and died on the southern border with Mexico while in the custody of the Department of Homeland Security. A final report on that case is pending.

The CDC doesn’t know the exact number of people who have been sick and affected by influenza because in most parts of the country, it is not on the list of diseases that must be reported to health authorities. Agency officials use a mathematical model based on rates of laboratory-confirmed influenza-associated hospitalizations.

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