H1N1 influenza shifted to younger people

TEMPE, Ariz., July 1 (UPI) -- The newest strain of the H1N1 influenza reveals an age shift toward a younger population compared with seasonal influenza, U..S. researchers say.

The researchers say 87 percent of the deaths and 71 percent of the cases of severe pneumonia occurred in people ages 5-59.

"The data show that the vast majority of cases of severe pneumonia and deaths occurred among those ages 5-59, which is atypical when compared with the age pattern supported by seasonal flu," one of the researchers, Gerado Chowell-Puente of Arizona State University, said in a statement. "If resources or vaccine supplies are limited, focusing prevention efforts on these age classes must be considered."

Because achieving high vaccination rates before the fall is not feasible with current technologies, effective distribution of a limited vaccine and antiviral stockpiles will be crucial to mitigate a potential second pandemic wave, Chowell-Puente said.

"The seasonal influenza vaccination strategy focuses on the very young and the very old -- the most vulnerable populations," Chowell-Puente said. "This is not necessarily the case for pandemics as we showed in our study."

The findings compiled by Chowell-Puente; Stefano Bertozzi and Arantxa Colchero of Mexico's National Institute of Public Health; Hugo Lopez-Gatell, Celia Alpuche and Mauricio Hernandez of the Mexico Ministry of Health; and Mark A. Miller of the National Institutes of Health in Bethesda, Md., are published in the New England Journal of Medicine.