Obese people, along with those who have diabetes and other chronic diseases, may suffer disproportionately from the H1N1 virus (swine flu), according to a report by the Centers for Disease Control and Prevention (CDC).

The CDC analyzed data from 553 flu cases in California, taking a particularly close look at the 30 cases requiring hospitalization. Two-thirds of hospitalized patients had chronic underlying medical conditions (including four people with diabetes) or were pregnant.

Four of the hospitalized patients were obese. "We were surprised by the frequency of obesity among the severe cases that we've been tracking," said Anne Shuchat, a CDC epidemiologist. "I do think it's an important result."

The CDC plans to assess whether obesity should be included in the list of flu complication risk factors used to make recommendations about flu shots.

It was not considered surprising that people with chronic diseases or pregnancy made up a large portion of the hospitalized cases. These factors are known to make seasonal flu more severe, and it appears this swine flu outbreak is no exception.

The full report can be downloaded here.