WEDNESDAY, May 6 (HealthDay News) -- While the large majority of U.S. cases of swine flu continue to be mild, those who are hospitalized with more severe disease appear to be atypically young, federal health officials said Wednesday.
The median age of hospitalized individuals with swine flu is 15, which is younger than occurs with regular seasonal flu, Dr. Richard Besser, acting director of the U.S. Centers for Disease Control and Prevention, said during an afternoon news conference.
"We are seeing the same distribution in hospitalized patients as we are in milder cases in the community, and that's younger than what you would see in seasonal flu," Besser said. "In seasonal flu you tend to see a predominance of burden of disease in the elderly and in the very young, and here we are seeing it more in the younger population."
"That is something we are keeping our eye on. That is something that raises concern," he added.
Overall, the age spread for hospitalized patients ranges from 8 months to 53 years of age, Besser said. Why the more severe cases are skewing young remains unclear, he said, but it could be that younger people are getting sicker sooner, or older people may have some kind of built-in immunity.
In any case, the U.S. outbreak of H1N1 swine flu is continuing and, although most cases are still mild, more deaths are expected, Besser said. "We remain concerned," he said. "We are seeing continued spread around the country. We are seeing increases in numbers of patients."
The death earlier this week of a woman in Texas, the first U.S. resident to die from the swine flu, "reminds us that influenza can be a very serious infection, and it's one we need to continue to take very seriously," Besser added.
According to the Associated Press, Texas health officials have not said that the death of 33-year-old schoolteacher Judy Trunnell was directly caused by the H1N1 flu, noting that she also had unspecified "chronic underlying conditions."
Late Tuesday, reports surfaced that the government would ask Americans to get three vaccinations for the upcoming flu season -- one for the seasonal flu and two for this new strain of H1N1. However, on Wednesday Besser said that it was premature to make that decision.
"Before a vaccine is administered there are a series of studies that need to be taken. These are under the direction of the National Institutes of Health and approved by the Food and Drug Administration. They need to do studies to determine how much of the antigen needs to be in the vaccine to stimulate protection," he said.
"They will also need to see -- do you get sufficient immunity from one dose, do you need more than one dose," Besser said. "With each vaccine it's different, with different age groups it's different. It's really early to say how many vaccines someone is going to need until those studies are done," he said. "Hopefully, we will be able to find a vaccine that worked with one dose."
Besser said that, as of Wednesday, the CDC was reporting 1,487 probable and confirmed cases in 44 states. "That's an increase of around 400 from yesterday. There are around 850 probable cases and 642 confirmed cases. The confirmed cases are in 41 states," he said.
In addition, there are 35 confirmed hospitalizations from the flu and an additional 17 probably caused by flu, Besser said. Much of the increase in cases is due to catching up on testing, but there is a real increase in disease too, he said.