Q:There seems to be a popular belief that children can catch polio from swimming pools. The virus is supposed to get into the pools when newly vaccinated children excrete the live virus. My medical dictionary says that polio is excreted in the stoo

A:This widely circulated myth is usually used as rationale for having babies vaccinated with the live polio virus (so that they don't catch it when they swim). We checked with the Physician's Desk Reference under the entry for Orimune, the live pilovirus vaccine produced by Lederle. According to Lederle, "The vaccine viruses are shed in the vaccinee's stool up to 6 to 8 weeks as well as via the pharyngeal route." That means, the drug is also excreted via the throat.

We then consulted with our expert on all vaccine matters, former FDA official Dr J Anthony Morris. He put this so called risk into perspective. First of all, the virus usually shed by recently vaccinated babies is the same attenuated (weakened) one that they have been given. On very rare occasions the vaccine virus mutates in the gut of a vaccine recipient and reverts to its virulent form. Dr Morris says:

"Polio virus is mainly transmitted through fecal matter, not through urine. Although many babies urinate in pools, few defecate in them.

"However, should any of the polio virus become circulated and somehow make its way into the pool, the level of chlorine in most swimming pools added to kill most infectious diseases should be adequate to inactivate it.

"So if there is any danger at all, it is so minute that you can forget about it"

Dr Morris adds that there is less risk of contracting polio from a pool full of newly vaccinated children than from the vaccine itself.

One final note. Remember that in most cases, polio is a harmless infection. The current statistics estimate that only 10 per cent of people exposed to polio will contract it, and only l per cent of these will come down with the paralytic variety those that vaccine critic Dr Richard Moskowitz says have a certain "anatomical susceptibility". Furthermore, the Centers for Disease Control in the US estimates that the risk of vaccine induced polio is one per 500,000.

To err on the side of safety, it''s probably prudent to keep all unvaccinated people out of pools frequented by lots of three month old babies who may have recently been vaccinated. If you or other unvaccinated individuals are going to be handling recently vaccinated babies, you may wish to get your immunity to polio checked out and consider having the new killed polio vaccine, which doesn't carry the risk of contracting paralytic disease.