TUESDAY, Sept. 7 (HealthDay News) -- The H1N1 pandemic flu, which swept across the United States last year, was actually no more serious than most seasonal strains, a new study confirms.
According to the U.S. Centers for Disease Control and Prevention, there were 43 million to 89 million cases of the H1N1 pandemic flu in the United States from April 2009 through April 10, 2010. Of these, an estimated 274,000 were hospitalized and 12,470 died.
"We found that the pandemic H1N1 virus disproportionately affected children and young adults, but the symptoms and risk of most complications were similar to those of seasonal influenza viruses," said lead researcher Dr. Edward A. Belongia, from the Marshfield Clinic Research Foundation in Marshfield, Wisc.
In fact, children, young adults, pregnant women and people with underlying chronic medical conditions had a higher risk of hospital admission and serious complications when infected with the pandemic virus, the researchers noted.
However, whether the pandemic flu was deadlier or caused more critical illness than the simultaneously circulating seasonal strains has not been studied until now, Belongia noted.
"One implication is that the higher incidence of death or serious illness from the pandemic H1N1 infection in other studies may have been due to the high level of transmission in susceptible children and young adults rather than greater virulence of the pandemic virus," he said.
However, this study did not address specific high-risk populations such as pregnant women, Belongia said.
The report is published in the Sept. 8 issue of the Journal of the American Medical Association.
For the study, Belongia's group compared the H1N1 pandemic flu with the seasonal H1N1 flu, as well as the H3N2 seasonal flu.
Out of 6,874 people who agreed to take part in the study, the researchers found 545 pati
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