Citing diminishing sales, GlaxoSmithKline pulled the only available Lyme disease vaccine, Lymerix, off the market Tuesday. The U.S Food and Drug Administration (FDA) first approved the controversial vaccine in 1998. Lyme disease is transmitted to humans through the bites of ticks infected with the bacterium Borrelia burgdorferi. Lymerix contains a genetically engineered protein that stimulates antibodies that disable the bacterium.

Shortly after Lymerix was introduced, patients who received the vaccine began to complain of adverse side effects, including symptoms similar to Lyme disease itself. Reports of muscle pain, arthritis and allergic reactions in Lymerix users caused alarm in the medical community. While the vaccine's connection with such conditions is still subject to debate, GlaxoSmithKline's decision to pull Lymerix was supported by several pharmaceutical industry critics. A spokesperson for the Lyme Disease Foundation said the vaccine "was never safe, nor was it effective."

Lyme disease, which is rarely fatal, typically causes a characteristic "bull's eye" rash and flu-like symptoms in the early stages of infection. Occasionally facial weakness and heart problems also occur. In the later stages of the disease, sometimes months or years after initial exposure, some patients develop chronic arthritis and neurological problems.