You may have heard or read news reports, such as the one in the Washington Post, announcing the findings of a Centers for Disease Control (CDC) survey, which found that obesity “is as much of a risk factor for serious complications from the [swine] flu as diabetes, heart disease and pregnancy, all known to raise a person’s risk.” But I suggest you take the CDC report with a large grain of salt because the survey was based on a very small number of patients and was not designed to provide data from which such conclusions could be drawn.

The survey looked at only 30 patients hospitalized with swine flu in California. Of those, only four were obese. So the conclusion that obesity might be an independent risk factor for severe swine flu was based on four patients! Not only that, but according to the data table contained in the CDC report, “Conditions listed are not mutually exclusive; certain patients had multiple underlying chronic diseases.” That means it’s possible some of the four obese people might also have had other risk factors, which confounds the data. Unfortunately, however, they don’t provide the details so it’s impossible to know whether the patients each were just obese or if they had obesity and one or even several other risk factors. And whether they did or did not have only obesity as a risk factor, remember that the researchers looked at only 30 people and of those only four were obese. While it may eventually be shown that obesity is a risk factor for more severe swine flu, I think we don’t yet have the data to make such sweeping conclusions.

In another announcement, the CDC is saying that people born before 1957 seem to be at lower risk for swine flu than those who are younger. The reason for this, which seems to be based on much more solid evidence than the obesity story, is that older adults may have partial immunity against the swine flu virus because they were likely to have been exposed to a somewhat similar virus that circulated between 1918 and 1957. It turns out that the 1918 influenza pandemic was due to an H1N1 flu virus, and the current swine flu is also an H1N1 variant (but not exactly the same as the earlier one). To date, only 13 percent of U.S. patients hospitalized with the new flu are age 50 or over while 37 percent of patients are between the ages of 19 and 49 years old, 18 percent are between 10 and 18 years old, and 11 percent are between 5 and 9 years old. This pattern is similar to that of the 1918 pandemic in which death rates were highest among younger rather than older adults. Similarly, those who were older in 1918 may have been exposed to another similar virus that circulated in the late 1800’s and therefore already had immunity. The CDC report on lower risk in those born after 1957 is expected to be published today, May 21.

The swine flu story is still evolving and we are learning new things every day. Some conclusions may be based on more solid data than are others, as we’ve seen above with the shaky story on obesity increasing risk and the more reasonable one on older age decreasing it. You can stay up to date here on EverydayHealth.com where our swine flu center has all the news and information you need to keep you and your family safe and healthy.

everydayhealth.com