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The midcoast has the highest rates of tick-borne illnesses in Maine, which is why the state’s biggest health care system chose its Rockport hospital — Pen Bay Medical Center — as the site for research on a proposed new vaccine for Lyme disease.
If the vaccine is determined to be safe and effective, it would be a huge advance, as there has not been a Lyme disease vaccine on the U.S. market in more than two decades.
About 80 people are involved in the trial at MaineHealth’s Pen Bay Medical Center, which is part of a national study of a Lyme vaccine called VLA15 developed by the companies Pfizer and Valneva, according to Dr. Robert Smith, who’s working on the trial team. In total, the study is testing the safety and effectiveness of the shot on nearly 9,500 people across the country.
Smith, who is the director of MaineHealth’s Vector-Borne Disease Laboratory, said part of the reason the Rockport facility was chosen is because Knox County shows the highest per-capita rates of confirmed Lyme disease in the state.
As of July 15, there had been 135 cases of Lyme confirmed in Knox County so far this year, which translates to a rate of 328 cases per 100,000 people — the highest in Maine, according to data from the state Center for Disease Control and Prevention.
Several other coastal counties also lead the state in Lyme disease rates for this year, with 251 cases per 100,000 in Lincoln, 247 per 100,000 in Hancock and 216 per 100,000 in Waldo, according to Maine CDC.
“We’re clearly a population that is a good one to offer the enrollment and the trial for,” Smith said.
The last Lyme disease vaccine to hit the market was in 1998, Smith said, and was around for four years until it was removed due to lack of interest, since the illness was not as common at the time. That vaccine only targeted North American strains, but nearly 80 percent of people who took it were protected from the bacteria that causes the disease, he said.
This time around, as warmer, wetter weather brought on by climate change is helping ticks and the diseases they carry to spread, the new vaccine is supposed to protect against both North American and European strains of Lyme disease, Smith said. The trial is testing children as well, as they are particularly susceptible.
As far as Smith knows, this is the only vaccine for Lyme disease in its final phase of trials. In addition, the medical school at the University of Pennsylvania is developing an mRNA vaccine that has completed preclinical animal trials.
Once people have had the vaccine being tested in Maine, antibodies in their blood attack the Lyme disease bacteria inside a tick that bites them, preventing any of it from reaching the person, according to Smith.
The people involved in the trials are particularly susceptible to tick bites because they frequently spend time outdoors, Smith said. Half of the participants are randomly selected to receive the vaccine, while the rest receive a placebo. Participants receive three shots within the first year, then a booster shot about a year after the completion of the first immunization.
Researchers then monitor the antibody response in the participants, Smith said. And, if a participant thinks they may have contracted Lyme disease after a tick bite, the researchers test the person to verify that.
The goal is for the vaccine to show a statistically significant decline in cases of Lyme disease. Smith said the trials are expected to conclude by the end of 2025, which is when Pfizer will submit the vaccine to the U.S. Food and Drug Administration for approval.
“The range of risk in the United States has expanded, the number of cases has expanded, public concern has increased,” Smith said. “I think we’re at a time when there will be interest in Lyme vaccines.”
