With the potential for causing a variety of lingering symptoms ranging from lethargy to nervous system damage, Lyme disease has become a perennial concern for people venturing outdoors in the summer months. Carried by deer ticks, the Borrelia burgdorferi bacteria can challenge our immune systems and prove frustrating to treat. About 30,000 cases are reported to the CDC each year, although the total cases of unreported transmissions could be ten times that number.

So why don’t we have a vaccine for it? We did. And it disappeared.

According to Vox, the spread of Lyme cases in the 1990s compelled pharmaceutical company GlaxoSmithKline to research and develop a vaccine called LYMErix that attacked the outer protein present in the bacteria. It did so by becoming proactively aggressive, killing off the bacteria while it was still in the body of the attached and feeding tick. More than 1.5 million people were given the vaccine before 2000. Clinical trials demonstrated up to a 90 percent success rate.

While that kind of efficacy and protection would be welcome today, at the time doctors weren’t quite certain what kind of demographic they should be recommending the vaccine to: There was less information about regional areas of tick concentrations than there is now. The vaccine also required three doses in the span of a year, making it slightly inconvenient; some health insurers resisted the $50 cost for each injection.

Those issues were surmountable over time. But some members of the Food and Drug Administration (FDA) panel that had approved the vaccine voiced concern that LYMErix might potentially attack healthy proteins in the body. This autoimmune reaction was never demonstrated in trials, but the theory made consumers wary when it was publicized in the media, and some of those treated complained of arthritis symptoms. Coupled with increasing scrutiny and apprehension over vaccines in general, LYMErix failed to become a staple of vaccination schedules. Sales dropped and GlaxoSmithKline stopped production. With the patent having expired, it’s not likely drug companies will be interested in resurrecting it, only to face additional bad press. Alternative vaccines are being considered, but could take years before coming to market.

In the absence of an effective vaccine, the best way to ward off Lyme remains prevention. If you’re going to be in wooded areas where the ticks tend to congregate, wearing light-colored clothing will help you spot the small nymphs. Insect repellent is important, and examining your body—particularly behind the ears and armpits—for ticks after being outside is also a must. If you find one, remove it with a pair of tweezers.

For more information about Lyme disease, check out our 15 Useful Facts.

[h/t Vox]