Ticks

BOSTON (CNN) -- The spread of Lyme disease, a tick-borne disease that infects thousands of Americans each year, may soon be under attack from two new vaccines.

Results of a preliminary tests, published in this week's New England Journal of Medicine, shows competing vaccines LYMErix, produced by SmithKline Beecham, and ImuLyme, made by Pasteur Merieux Connaught, appear equally effective in protecting against the disease.

Ticks, often no larger than pinheads, spread the Lyme disease germ that strikes 10,000 Americans a year, mostly in the Northeast. Left untreated, it can lead to arthritis and even life-threatening complications.

The two vaccines await government approval, and neither is on the market yet. In May, a Food and Drug Administration advisory council recommended LYMErix. ImuLyme is up for review.

"The way it seems to work is that it deactivates the organism within the tick before the tick has a chance to spread the organism through the tick bite into the unwitting host," said the director of the study, Dr. Leonard H. Sigal of New Jersey's Robert Wood Johnson Medical School.

Deer ticks

The study shows both vaccines are more effective after the second year -- with a booster shot. LYMErix was found 76 percent effective in protecting against the disease, and ImuLyme was 92 percent effective.

However, Sigal said the two volunteer groups who tested the vaccines were not identical and that may account for the difference.

"I don't think one can say one vaccine is better than the other," he said. Both vaccines require three shots; side effects are limited to sore arms and occasional mild fever.

Since no vaccine is perfect, Sigal recommended people still use common sense to avoid tick bites.

"Do a tick check; take a shower at the end of the day and use a washcloth because you can knock the tick off before it even gets a chance to get hold of you and take a bite," he said.