Clinical trials conducted at Yale over the past two years have proven the effectiveness of two Lyme disease vaccines—one developed by Yale faculty—the first such drugs of their kind. Advisory panels have now endorsed both vaccines and the pharmaceutical companies that own the drugs are awaiting FDA approval to begin marketing them.

In studies at Yale and other centers involving more than 20,000 people over two Lyme disease seasons, the vaccines were found to prevent the disease in a majority of cases. The Yale vaccine, LYMErix, was found to prevent 76 percent after three injections. SmithKline Beecham has obtained exclusive licensing to the Yale vaccine.

ImuLyme, a vaccine developed by Pasteur Merieux Connaught of Swiftwater, Pa., was found to prevent Lyme disease in 68 percent of cases after two injections and 92 percent of cases after a third dose. Differences in efficacy between the two vaccines could be due to varying methods of surveillance. ImuLyme excluded people over 65, while LYMErix included all adult age groups.

The results of the studies were published in the July 23 issue of The New England Journal of Medicine.

“These two studies demonstrate that vaccination can be an important new approach to preventing Lyme disease, which is the most common tick-borne disease in the United States,” said Robert T. Schoen, M.D., clinical professor of internal medicine and a member of the team that studied the Yale vaccine.

Lyme disease was first identified by Yale researchers Stephen E. Malawista, M.D., and Allen C. Steere, M.D., in 1975. The vaccine was derived from basic research performed at the School of Medicine by a team including Richard A. Flavell, Ph.D., professor and chair, section of immunobiology, Fred S. Kantor, M.D., the Paul B. Beeson Professor of Medicine, Erol Fikrig, M.D., associate professor of medicine, and Stephen W. Barthold, D.V.M., Ph.D. This work was supported by grants from the National Institute of Health and the Centers for Disease Control, as well as a generous grant from the Mathers Foundation.

Both vaccines stimulate immune responses to produce antibodies against Lyme disease. The vaccines not only provide immunity, but also may kill the spirochete, the bacterium in the mid gut of the tick that causes Lyme disease.