Two similar vaccines are being tested against the bacteria transmitted by the tiny deer tick that causes Lyme disease.

But how effective either is remains an unknown:Half the volunteers receive the vaccine in a shot; half get a salt solution, and researchers are keeping themselves in the dark, as well, at this point, to ensure no bias.

Each vaccine will be tested on about 10,000 people over two years.

Advertisement

One trial, begun last year by Connaught Laboratories of Swiftwater, Pa., includes people at 13 sites, most of them in the Northeast where Lyme disease is endemic. Volunteers were given a shot last year and a booster this year.

The study should be completed late this year, but it will be two years or more before the data are thoroughly analyzed and examined by the Food and Drug Administration.

Smith Kline Beecham of Philadelphia began a two-year trial of its vaccine several months ago. It will include people at 35 sites, most in the Northeast.

Dr. Raymond Dattwyler, director of the Lyme Disease Center at University Medical Center at Stony Brook, N.Y., said he doesn’t have high hopes for either vaccine.

Both vaccine trials are immunizing against one strain of the bacteria. But we don’t know how many strains there are.

We know three strains have been well-defined that cause disease in humans. However, there are substrains still being defined, he said.