Robert Roos * News Editor
Dec 10, 2009 (CIDRAP News) – Another month's worth of data on H1N1 influenza has led federal officials to more than double their estimates of total cases, hospitalizations, and deaths and to assert that the impact on children and younger adults has been far greater than that of a typical flu season.
After analyzing data for the weeks from Oct 18 through Nov 14, the Centers for Disease Control and Prevention (CDC) estimated that 47 million people, or about 15% of the population, have been infected and 9,820 have died in the pandemic. That compares with estimates of 22 million cases and 3,900 deaths issued Nov 12 and covering the period from April through Oct 17.
The new estimate of hospitalizations is 213,000, compared with 98,000 a month ago.
"By Nov 14, many times more children and younger adults, unfortunately, have been hospitalized or killed by H1N1 influenza than happens in a usual flu season," CDC Director Dr. Thomas Frieden said in a news briefing today.
The additional weeks covered in the latest report spanned the peak period for the fall wave of H1N1. In terms of the number of states reporting widespread activity, the last 2 weeks in October marked the crest, with 48 states in that situation. The number dropped to 43 states by the second week in November and has declined further since.
16 million cases in children
In an online report, the CDC estimated there have been 16 million cases in children up through age 17, leading to 71,000 hospitalizations and 1,090 deaths. For adults age 18 through 64, the agency estimated 27 million cases, 121,000 hospitalizations, and 7,450 deaths.
For elderly people, who are believed to have some protection form the virus because of past flu exposures, the new estimates are 4 million cases, 21,000 hospitalizations, and 1,280 deaths.
Less than 5% of the increases in total cases, hospitalizations, and deaths are explained by late reporting of events that occurred before Oct 17, the CDC report says. Frieden commented, "There is some correction for late reporting. But there has been a lot more disease in the month that's reported than in the months before."
All the numbers represent the midpoints of ranges of estimates the CDC produced with a new estimation method, which was unveiled Nov 12. The numbers of confirmed cases and related hospitalizations and deaths are far lower, because most people infected, including some who get severely sick, are not tested.
Source: http://www.cidrap.umn.edu/cidrap/content/influenza/swineflu/news/dec1009estimates-jw.html 
