The opportunistic flu virus

Posted on: July 6, 2009 6:36 AM, by revere

Flu virus is opportunistic. It takes advantage of any weakness. Seasonal flu picks on the very old and the very young, but pandemic flu has found us old folks tough and the younger amongst us quite tasty. No natural resistance seems to be a flavor enhancer. And pre-existing medical conditions? Quite delectable. So how full is the menu in the prime age range? CDC has just released one of their Quickstat summaries based on household interviews with a sample of the civilian, noninstitutionalized, adult U.S. population. The question the sample was asked was whether a doctor or other health professional had ever said they had any of a list of chronic conditions. If the answer to asthma was "yes," the follow-up question was, "Do you still have asthma?" Here are the results for young adults, those between the ages of 18 and 29 years old, also a prime age group for the swine flu virus:

Source: QuickStats: Percentage of Young Adults Aged 18--29 Years with Selected Chronic Conditions, by Sex --- National Health Interview Survey, United States, 2005--2007

Even in this relatively young and healthy age group, about one in six people has an underlying medical condition that might put them at greater risk for an adverse outcome from swine flu. The most frequent is asthma, a pulmonary condition of special pertinence for a virus that infects the respiratory tract. Women are more likely than men to have one of these conditions and not on the list is a physiologic condition that increases the risk from flu: pregnancy. There are about 500,000 women pregnant in any one month, a good fraction in this age group. Of course having a medical condition or being pregnant is not a requirement for a bad flu outcome. Around a third of the hospitalizations and a significant number of fatalities are in younger people without any pre-existing medical conditions. While for most people infected the clinical course is uncomplicated and self-limited, there are many for whom that is not the case.

It's a numbers game. The more lottery tickets, the more "winners." The problem with a pandemic is that the ticket holders are much younger than we are used to with seasonal influenza. Something to think about.