Researchers are seeking thousands of volunteers in the U.S. and Europe to test the first potential vaccine against Lyme disease in 20 years.

The shot developed by Pfizer and a French biotech company aims to block Lyme spread while a tick is biting.

The new study will test three initial doses between now and next spring, and then a booster dose a year later.

The only prior Lyme vaccine for people, made by another company, was pulled off the U.S. market in 2002.

With Lyme a growing threat, officials say it’s time to try again.

About 100 Maine residents will participate in the 13 month-trial.