CDC: Flu outbreak on decline
Sandy Voss of Holland, Michigan, comforts her sons Tyler, left, and Alec after receiving flu shots.
(CNN) -- Influenza activity appears to be on the downturn in the United States, even as federal officials report more than 90 children have died of the flu this season.
The Centers for Disease Control and Prevention said that 38 states still had widespread activity, down from 42 reported previously.
"We are cautiously optimistic that at least in some parts of the country, influenza may have peaked," CDC chief Dr. Julie Gerberding said Thursday. "But there's still plenty of flu out there, and we're still encouraging people with flu-like illness who meet the criteria for concerns or complications to be sure and seek medical attention if they do develop the illness."
So far, 93 children under the age of 18 have died of the flu this season, with about 60 percent of them younger than 5. Whether this number is comparable to past outbreaks or is unique to this season is hard to tell, Gerberding said. The agency normally doesn't track children's flu deaths so no firm figures for the past exist.
The CDC said that further studies on the impact flu has on children were in development, as well as ways to determine risk factors for severe illness and hospitalization.
This year's outbreak began earlier than usual and has spread more widely than usual, but it's not certain if this flu season will be more severe than past outbreaks, or if it just peaked early. On average, flu kills about 36,000 people in the United States each year.
"Even though we're hoping that we're past the peak for this early phase of the season, in past years we have seen flu come back," Gerberding said. "And we've also seen new strains emerge late in the season. So it's still important to be vigilant."
Before the new CDC numbers were released, Dr. Anthony Fauci -- director of the National Institute of Allergy and Infectious Diseases -- said that the flu season's severity and length is never predictable, but there are some signs to look for.
"When you see states that have widespread activity, when they start to turn the corner, then you have a pretty good indication that we're going in the right direction," he said on CNN's "American Morning."
The especially virulent strain of the virus that is predominant this season was not included in this year's flu vaccine. Fauci said efforts were being made to remedy that and to develop new ways of making the vaccine.
"That's the thing that from the research standpoint we are working on very diligently right now," Fauci explained. "Of developing new types of approaches, of being able to quicken and give greater efficiency to the process of being able to identify the strain and getting it into the vaccine in time."
Reports of an early and severe flu season sent the demand for the flu vaccine soaring, resulting in long lines for those waiting to be vaccinated and shortages of the shots. The government purchased additional doses in December to bolster states' supplies.