A federal public health official said Tuesday the approximately 5,000 confirmed cases of H1N1 flu in the United States is "a great underestimate" and the actual number may be about 20 times as high as that number.
Dr. Anne Schuchat, deputy director of the Centers for Disease Control and Prevention's Science and Public Health Program, told NPR that the number of flu cases is probably about 100,000, but most of those who have been sickened by the virus haven't been tested and are not part of the daily reports.
"We think that the numbers that we are reporting each day — some 5,000, or so, cases — are a great underestimate of the total burden that this virus is causing in our communities," Schuchat said.
Symptoms of the disease range from mild to severe, with some of those infected not being sick enough to seek medical care and others requiring hospitalization.
"We've estimated it [the number of flu-infected persons] might be something like 100,000 or more at this point, but that's a moving target."
CDC experts are looking at systems that track influenzalike illnesses and at trends that show the flu increasing in some areas and decreasing in others.
Schuchat said the number of cases is likely to grow, as new outbreaks are reported almost every day without signs of a lull.
"I think we're still in a full season of this new H1N1 virus. By this time of the year, the regular flu season is usually over," she said.
World health officials have set the number of confirmed cases globally at 9,800, with at least 80 confirmed deaths.
Schuchat said CDC officials are waiting to see if the summer months bring a decrease in the flu numbers.
In the meantime, they are focusing on the public health response, collaborating with health officials in the Southern Hemisphere and preparing for the fall flu season.
She said vaccine development and production and deciding whether a vaccination program is in order are at the top of the list of priorities.