Two vaccines designed to protect humans against Lyme disease have been shown to be effective in tests at the School of Medicine, where one of the vaccines was pioneered and where the tick-borne illness first was described in 1975.
The genetically engineered vaccine LYMErix™, based on discoveries by Yale researchers, prevented 49 percent of definite Lyme disease cases after two injections and 76 percent after a third injection in the second year of a study involving people between the ages of 15 and 70. Furthermore, the vaccine prevented 100 percent of cases of asymptomatic infections, which is considered significant because people who do not know they have been infected can develop health problems months to years later.
SmithKline Beecham has applied to the U.S. Food and Drug Administration for a license to market LYMErix™, which could make it the first Lyme disease vaccine to reach the market if approved. (SmithKline Beecham is exclusively licensed under Yale's Lyme disease patent applications.) In May, a Federal Drug Administration advisory committee found the vaccine safe and effective in the population studied and recommended its approval.
According to results published in the July 23 issue of The New England Journal of Medicine, the second vaccine prevented 68 percent of Lyme disease cases after two injections and 92 percent after a third dose. Differences in efficacy between the two vaccines may be due to varying methods of surveillance, according to an accompanying editorial. For example, data that could be used to identify asymptomatic infections were not provided for the second vaccine.
"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," says Dr. Robert T. Schoen, clinical professor of internal medicine and a member of the team that studied LYMErix™. Yale rheumatologist Dr. Erol Fikrig, one of the pioneers of a vaccine, also was a member of the research team.
Yale was one of many sites involved in clinical trials for the vaccines, which extended over two Lyme-disease seasons and involved more than 20,000 people in 10 states. In addition to enrolling and vaccinating volunteers in the trials, Yale researchers performed the immunogenicity tests required to measure the level of antibodies formed in response to vaccination. Yale researchers now are participating in a trial of LYMErix™ to determine the need for booster doses.
It was 13 years ago that Yale researchers Dr. Stephen E. Malawista and Dr. Allen C. Steere first identified Lyme disease, which is transmitted by ticks infected with the bacterium Borrelia burgdorferi. People with the infection often develop a rash known as erythema migrans, which may be accompanied by headache, fever, fatigue, and muscle and joint aches. The most serious cases may result in neurological disorders, arthritis or heart problems. Cases of Lyme disease have been reported in 48 states with 16,461 cases reported to the Centers for Disease Control and Prevention in 1996 alone.
Over the past two decades, Yale researchers have tracked the spread of the disease and determined the usefulness of antibiotics in treating it. In fact, Malawista, a member of the team reporting this week on the second vaccine, showed in 1980 that antibiotics almost always cure the disease in its early stages and are usually effective in later stages as well.
Today the University is home to one of the largest concentrations of Lyme-disease researchers in the world, and researchers affiliated with Yale's Lyme Disease Consortium have authored more than 200 papers on the disease and related topics.
"Yale has made a major commitment to combating Lyme disease through
diagnosis, treatment, and now also prevention," says Schoen. "That
commitment clearly is producing a benefit for public health."
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