http://online.wsj.com/article/SB125683072097816241.html?mod=googlen...

H1N1 Cases Vastly Underreported, CDC Says

The number of confirmed cases of H1N1 flu from April to July represents just 2% of the actual people who were infected with the virus, according to a report by the Center for Disease Control and Prevention.

The report, posted to the agency's Web site, says the number of people infected with H1N1 flu from April to July likely was between 1.8 million and 5.7 million, much higher than the 43,677 confirmed cases. The paper also said the virus hospitalized 9,000 to 21,000 people during the same period.

The study shows the prevalence of the virus is more widespread than originally reported. The CDC and World Health Organization in July stopped tracking individual cases because they acknowledged doing so was difficult.

In recent weeks, government health officials have instead been describing the scope of the virus by saying it is widespread in 46 states. The authors of the study say the report may help health officials plan for a subsequent wave of the epidemic in the fall and winter months.

Steve Brozak, an analyst and president of WBB Securities LLC, said the report shows there are just "too many variables" for the government to track individual cases, and suggests the government can't be held accountable if the disease becomes more or less widespread than health officials estimate.

"Now there's just no way you can say statistically we should have done this or done that," Mr. Brozak said.

The report says underreporting may occurs for a handful of reasons, including because not everyone gets tested and the quality of tests varies.

The authors of the study created a model to estimate cases based off the number of confirmed reports and other studies, such as the rate at which people with the season flu seek help.

The study estimates that for every confirmed case, there was likely a median of 79 actual people infected with the virus. Using the same model, the authors estimate about 800 people died from the virus during the same time frame.