Who Should Get Flu Shots?

It sounded like a good idea when New York City's Mayor, Rudolph Giuliani, advised New Yorkers last week to get a flu shot. After all, 20,000 Americans each year die of influenza. And this year in particular, the mayor suggested, getting a flu shot might be an especially good idea, since it could help doctors distinguish between flu and the deadly inhalational form of anthrax. How? Both anthrax and flu exhibit strikingly similar symptoms--fever, chills and muscle aches--in the early days of the infection. Physicians would be quick to suspect anthrax in anyone who was vaccinated against flu and still developed fever and chills. That would give them a better chance to identify any new victims of terror while their infection was still in its earliest, most treatable stages.

Or so the mayor's reasoning went. Unfortunately, there are a couple of problems with his logic. For one thing, getting vaccinated against influenza doesn't guarantee you won't get sick. Although highly effective, the flu vaccine protects against only the dominant strains and even then does not provide 100% protection. It takes a couple of weeks for your body to respond to the vaccine with a sufficient number of antibodies. Each year thousands of people who get the vaccine nevertheless still get the flu.

There are also plenty of reasons you might develop fever, chills and muscle aches that have nothing to do with either anthrax or flu. Indeed, doctors estimate that more than 80% of all flulike ailments each winter are caused by other groups of viruses, like the parainfluenza and picornavirus families. Getting vaccinated against flu can't protect you against suffering from these other respiratory ailments.

In the worst case, asking all healthy adults to get vaccinated could actually backfire, leading to even more deaths if it means we run out of shots for those who are most vulnerable to the infection. Already there have been delays in getting this year's shipment of vaccine to clinics and doctors' offices. Those who should be at the front of the line include folks who are 65 or older, nursing-home residents and adults and children with chronic health problems, including asthma, kidney disease, heart disease and diabetes, as well as anyone who cares for or lives with such people. Flu shots are also important for men and women whose immune system is weakened by HIV or other conditions.

The best reason to get the flu vaccine is that it protects against most flus--not that you're worried about contracting anthrax. While inhalational anthrax has killed only four people so far, many more could be at risk from flu-related complications. There's no need to compound the tragedy by making this year's influenza epidemic any worse.

See Dr. Ian on NBC's Today show. E-mail your questions to him: ianmedical@aol.com