With the flu season still in full swing, as many as 17.8 million people — including 2 million more within the last week — have fallen sick with influenza since October in what the Centers for Disease Control and Prevention calls a "low-severity" season, officials said Friday.

Despite a milder season this year, the CDC warns that flu activity this week is the highest it has been all season and urges individuals to get a flu vaccine, use everyday preventive actions, and to use antivirals as recommended.

Influenza is "widespread" geographically in Puerto Rico and 48 states, meaning cases were reported in more than half the regions of the state, according to the CDC.

The flu is blamed for 11,600 - 19,100 deaths, with up to 221,000 hospitalizations and up to 8.4 million flu medical visits. The CDC says there have been 34 pediatric deaths this season.

The CDC found, however, lower percentage of outpatient visits, lower rates of hospitalization and fewer deaths attributed to pneumonia and flu compared with recent years.

Last flu season, which stretches from October to the end of May, an estimated 49 million Americans got sick, 23 million sought medical care and 960,000 were hospitalized.

While any flu activity is alarming, the CDC says, the overall hospitalization rate so far this season is 23.8 per 100,000 people compared to 30.5 per 100,000 at this period last year. The highest rate is among adults 65 years and older, accounting for 64 hospitalizations per 100,000 population.

With the exception of the 50-64 age group, where hospitalizations are about the same as 2018, the rates "are a lot lower than last season," the CDC says.

The CDC credits vaccines with helping blunt the impact of flu this year.

"Early estimates indicate that influenza vaccines have reduced the risk of medically attended influenza-related illness by almost half (47%) in vaccinated people so far this season," the CDC says.

For the first time, the CDC this year has been able to track key data in near real-time instead of waiting until after the season ends.

The latest report notes that flu vaccinations have reduced the rate of illness caused by the predominant, yet milder, Influenza A (H1N1) virus by about 46 percent among patients of all ages, and about 62 percent among children 6 months through 17 years of age.

While the H1N1 virus has predominated nationwide, the Influenza A (H3N2) has largely been confined to the southeastern states.

Nonetheless, the CDC's latest reports say influenza activity since December has "increased overall and remained elevated" through early February.

In January, in its look at the first round of data, the CDC had projected a milder season than last year, and that trend appears to persist as new information pours in.

That early report showed that as many as 7.3 million people had fallen sick with the flu since the season began in October, with an estimated 69,000 to 84,000 hospitalized.

One positive sign as flu season enters what is typically its worst period: More people have received flu shots this year than last. By November 2018, the CDC estimated that 44.9 percent of adults had been vaccinated. Only 37. 1 percent had done so even by the end of the 2017-18 season.

In the latest data, widespread influenza activity was reported by Puerto Rico and 48 states: Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin and Wyoming.

Widespread outbreak denotes flu or increases in influenza-like illnesses in at least half of the regions of a state.

Regional influenza activity was reported by West Virginia.

Regional outbreak means flu or increases in flu-like illnesses or confirmed influenza in at least two but less than half the regions of a state.