Lyme vaccine researcher Robert Smith in the lab at MHIR on Monday. Smith is the director of the Vector-Borne Disease Lab and is leading an assessment of a new blood test for early Lyme disease. Shawn Patrick Ouellette/Staff Photographer

MaineHealth is participating in a research trial that is testing the effectiveness of a potential new Lyme vaccine that could prevent thousands of cases of the disease each year in Maine if approved by federal regulators.

Dr. Robert Smith, director of the MaineHealth Institute for Research’s Vector-Borne Disease Lab in Scarborough, said the vaccine is showing promise that it will prevent Lyme disease. If proven safe and effective, it could be ready for public rollout in two to three years.

Ticks at MHIR where researchers are studying tick-borne illnesses and how climate change is increasing the number of ticks on Monday. Shawn Patrick Ouellette/Staff Photographer

Maine set a record for Lyme infections in 2023, with 2,943 reported cases of the disease, and the state has seen a steady rise in cases over the past decade. Lyme disease is transmitted to humans by the deer tick, and symptoms include a fever, headache, fatigue, joint pain, muscle aches and pains, and swollen lymph nodes. The symptoms often include a bulls-eye rash at the site of the tick bite but the rash is not always present.

If caught early, Lyme can be treated with a course of antibiotics. But some people experience chronic symptoms long after the infection has run its course.

Scientists have been working for years to prevent the disease through a safe vaccine.

“The early data is encouraging,” Smith said. “I’m hopeful that it’s going to really help in protecting people from Lyme disease.”


At MaineHealth’s Pen Bay Medical Center in Rockport, 84 patients were enrolled in Pfizer’s clinical research trial in 2023, with half receiving the Lyme vaccine and the other half getting a placebo. The vaccine trial enrolled 9,000 patients in the United States, Europe and Canada.

Those who got the vaccine or a placebo will be monitored for Lyme disease through December 2025, and results from the clinical trial will start becoming available in 2026. Separately, another potential Lyme vaccine being developed by Valneva also is undergoing clinical trials, the U.S. Centers for Disease Control and Prevention said.

If successful, the new drug would be the first Lyme vaccine available for use in humans since a previous Lyme vaccine was pulled off the market in 2002, although a vaccine for dogs remains available.

Staff Scientist Rebecca Robich works on DNA extraction in the lab at MHIR Monday. Robich is working this summer to determine the mammalian blood meal source for ticks infected with Powassan virus, a rare tick-borne virus that can cause encephalitis disease in humans. Shawn Patrick Ouellette/Staff Photographer

“It feels good to be part of helping to bring this to fruition,” said Caroline Knight, a registered nurse and research coordinator at Pen Bay. “Hopefully, we can all be vaccinated just like our dogs are.”

There were a number of reasons the previous human vaccine was removed from the market, Smith said, including misinformation that the vaccine caused Lyme disease, and that the disease had not reached the high number of cases now being reported, especially in the Northeast.

Knight said the new vaccine will likely be more effective than the previous one, which was only on the market for a few years starting in the late 1990s.



The Lyme vaccine would not protect against other common tick-borne diseases, such as anaplasmosis and babesiosis. There were 777 cases of anaplasmosis in Maine in 2023, and 194 cases of babesiosis.

MaineHealth also is participating in research that could see a more accurate blood test that could detect the presence of the Lyme bacteria, Borrelia burgdorferi. And another research study would try to determine the blood meal source of ticks infected with Powassan virus. Only a handful of cases are reported in Maine each year, and scientists are still learning about it and its potential, but Powassan virus can cause severe disease, including infection of the brain (encephalitis) or the membranes around the brain and spinal cord (meningitis), the CDC says.

Rebecca Robich, a research scientist at MaineHealth, said experts at first believed the Powassan virus was transmitted by ticks found on white-footed mice, but the evidence is so far not supporting that theory. So Robich said a team of researchers this summer in Maine will be testing ticks that carry the Powassan virus to see what animal they were previously attached to, including shrews, mice, voles, birds, deer, dogs and cats.

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