Counsel, Caveats From an Expert

By Shankar Vedantam
Washington Post Staff Writer
Tuesday, April 28, 2009

We posed a number of your questions about swine flu to Peter Palese, a microbiologist and infectious-diseases expert at Mount Sinai Medical Center.

Q. I had the swine flu shot during the previous outbreak in 1976. Am I still immune to this form of flu, or has the shot's effect worn off by now?

A. Good question. The answer is probably yes, you do have some immunity, although it has been 30 years. There are two caveats -- your immunity might be waning, and secondly, we do not know yet what the precise composition of the new virus is and how closely it matches the earlier swine flu outbreak.

Should I avoid air travel to Mexico and other places where there are outbreaks? Should we curtail air travel to places that have had swine flu outbreaks?

Wait to see what authorities tell us. [U.S. officials yesterday asked Americans to put off unnecessary travel to Mexico.] Curtailing air travel sounds good, but many people in the field actually believe this is not an effective way of quarantining an outbreak because the virus will still travel via cars, trucks, boats and other modes of transportation. Curtailing air travel, which can have very large costs, may only slow the arrival of a virus to a new location; it might not prevent it from arriving.

How effective are hand sanitizers in preventing transmission of swine flu?

Hand sanitizers are effective if used correctly -- they have alcohol in them. Hand washing helps, too, but there is also an aerosol component to the influenza virus. We can keep our hands in our pockets and still get influenza. At the same time, yes, we should practice hand hygiene as much as we can; besides conferring some protection against swine flu, it helps against other problems such as common colds and intestinal bacteria.

Do face masks do any good in protecting people from swine flu?

Face masks do one thing -- they protect people in terms of preventing other people from getting close to them. So you get a sphere of privacy from wearing a mask, but it's largely psychological. The masks do help if someone sneezes right at you. However, the pore size of these masks lets viruses go through. Again it is not a clear-cut yes or no; there is some benefit, but there is not as much benefit as we would like.

Can consuming lots of Vitamin C ward off a swine flu infection?

While a lot of people swear by Vitamin C, there is very little evidence that it works. But there is a placebo effect, which can be useful.

Are health recommendations for swine flu different for babies, toddlers, children or pregnant women?


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