An article in New Scientist suggests that people who are obese are twice as likely to die of swine flu, but that the results are reversable with excersise.
Mind you the researcher has also suggested stockpiling statins and described them as 'cheap and safe', but I have know several people who have had bad effects from them and not realised why till they were hard to reverse (who would connect a frozen shoulder, or a pain in the arm, or mental confusion, with a cholesterol reducing drug - the doctor didn't)