The flu is hitting young- and middle-aged adults harder than any other age group this flu season — representing 61 percent of all hospitalizations from influenza — according to the Centers for Disease Control and Prevention.
The 2009 H1N1 strain, also known as "swine flu," is the predominant strain this flu season, officials said, and it is hitting otherwise healthy individuals harder than other strains. In the three previous flu seasons, people 25 to 64 years old accounted for 18 percent, 30 percent and 47 percent of hospitalizations and deaths, respectively.
During the 2009 season, people 25 years to 64 years accounted for an estimated 63 percent of deaths.
"The bottom line is the flu can make anyone very sick, very fast and it can kill," said CDC Director Tom Frieden during a media briefing on Thursday.
Adults with underlying medical conditions such as asthma, lung disease, obesity and diabetes, as well as young children and the elderly, are among the most vulnerable for the flu, said Anne Schuchat, the director of the National Center for Immunization and Respiratory Diseases.
However, the flu vaccination is doing its job, she said. A vaccinated person is 60 percent less likely to have to go to the doctor for flu illness.
Vaccine effectiveness varies from year to year, she said, adding it can range anywhere from 35 to 60 percent. The CDC looks at global data to predict which strains will circulate each season before it makes the batch of vaccines. "It can be very difficult to predict," Schuchat said.
However, vaccination rates are lowest among those 18 to 64 years old. More than 60 percent of people over 65 years old have been vaccinated, along with more than 50 percent of children under 9 years old.
"We'd like to avoid someone knowing a person who has tragically dies before getting vaccinated," she said.
Flu shots prevented an estimated 6.6 million influenza-associated illnesses during the 2012-2013 flu season, the CDC said in December. Influenza vaccines reduced the number of flu illnesses and hospitalizations by 17 percent last year, preventing 3.2 million medically attended illnesses and 79,000 hospitalizations. This is higher than any other season for which the CDC has produced similar estimates
Flu surveillance data suggests that flu activity is likely to continue for several more weeks, especially in areas where activity started later in the season. Some states that saw earlier increases in flu activity are now seeing decreases while other states are still seeing high levels or continued increases in activity.
Iowa reported its first pediatric flu-related death in January. Flu activity in Iowa has slowed from earlier this year, according to the Iowa Department of Public Health's flu activity report. It was reported to be widespread in January and is now only regional.
Drug companies have made about 138 million doses of the vaccine and distributed 134 million of those doses, Schuchat said. This means vaccines still are available, even if they are harder to find."Vaccinated people are better off than those who are not vaccinated," she said.