ObeseObese people may be at particular risk of severe complications or even death due to the new H1N1 virus, U.S. researchers reported.

They described the cases of 10 patients at a hospital in Michigan who were so ill they had to be connected to mechanical ventilators. Three died. Nine of the 10 were obese, seven were severely obese, including two of the three who died.

The study, published as a weekly progress report of the Center for Disease Control and Prevention (CDC, for its initials in English) on deaths and infections, also suggests that doctors can safely double the usual dose of oseltamivir, medicine Roche AG sold under the name Tamiflu.

“What this suggests is that there may be severe complications associated with virus infection, especially in severely obese patients,” said CDC virus expert, Tim Uyeki.

Dr. Lena Napolitano Medical Center, University of Michigan and colleagues studied the cases of 10 patients admitted to the intensive care unit of the university with the syndrome of acute severe respiratory problems caused by infection with the H1N1.

“Of the 10 patients, nine were obese (with a BMI above 30), including seven who were extremely obese (BMI over 40),” they wrote in their report.

Their study was not designed to see whether obesity or some other factor represent a special risk for influenza. But researchers were surprised to see that seven of the 10 patients were extremely obese.

“It is not known whether obesity is an independent risk factor for severe complications in the new virus infection of a new influenza A (H1N1). Obesity has not been previously identified as a risk factor for severe complications from influenza seasonal “Uyeki said.