This flu season has been particularly severe for older adults, with this age group experiencing the highest rate of hospitalizations in a decade, according to a new report from the Centers for Disease Control and Prevention. 

Since October, the rate of flu hospitalizations among U.S. adults ages 65 and over has been 258 hospitalizations per 100,000 people, the report found. Previously, the highest rate was during the 2012 to 2013 flu season, when there were 183 flu hospitalizations per 100,000 people ages 65 and older, the report said. Health officials started keeping track of flu hospitalizations in 2005.

For the U.S. population as a whole, the flu hospitalization rate this season was about 52 hospitalizations per 100,000 people, which is higher than the rates for the past three flu seasons, the report said. [6 Flu Vaccine Myths]

One reason the flu is more severe this year could be the types of flu strains that are circulating. The most common strain of flu this season is H3N2, and health officials know that in years when this flu strain predominates, there tend to be more hospitalizations and deaths.

A study published earlier this year also found that this year's flu vaccine is not very effective at preventing the flu, likely because the strains in the vaccine are not a good match to the strains in circulation.

But the CDC still recommends flu vaccinations, because they still may prevent some flu infections. And people who get vaccinated and then do get sick with the flu may have less severe symptoms — and lower likelihood of hospitalization — than those who skip the flu shot, the CDC said.

It is also important that people who are hospitalized with the flu, or who get sick and are at high risk for complications from the flu, receive prompt treatment with antiviral drugs, the CDC said.

This flu season does not appear to be as deadly as previous flu seasons. This flu season, the proportion of all deaths in the United States that were attributed to pneumonia or influenza peaked at 9.3 percent, which is lower than during the 2012 to 2013 flu season, when the proportion reached 9.9 percent.

But this year's flu season is still not over. Health officials say that flu season could continue for a few more weeks.

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