Although Lyme disease is very rarely life-threatening, it can lead to chronic joint pain and neurologic symptoms, even in people who are treated with the recommended course of antibiotics. If left untreated, the infection spreads to the joints, heart and nervous system and can lead to more serious complications.
Lyme Disease Cases on the Rise
Lyme disease experts say a vaccine against Lyme disease could help reduce case numbers in states with high case counts, like Wisconsin. In 2021, there were nearly 5,000 estimated cases of Lyme disease in the state, and cases more than doubled over the last 15 years, according to the Wisconsin Department of Health Services. Experts say one reason for the rise in cases is the increase in the geographic distribution of the ticks that transmit the bacteria that causes Lyme disease, called Borrelia burgdorferi.
“Today’s risk of Lyme disease is higher than it used to be,” said Jenifer Coburn, PhD, a professor at the Medical College of Wisconsin who studies Lyme disease-causing bacteria. “In addition to the ticks’ broader geographic range, the increase is also due to the expanded human occupation of former wild lands, which increases human exposure to ticks that would normally feed on wild animals. A third factor is climate change. Warmer temperatures over the winter months promote survival of ticks and the wild animals they feed on.”
Lyme Disease Vaccine in Clinical Trials Kills Bacteria in Ticks When They Bite Humans
A Lyme disease vaccine is available for dogs, but there is not one available for people. The only way to prevent Lyme disease infections in humans is to try to prevent tick bites. Prevention measures include using insect repellant containing at least 20% diethyltoluamide (DEET), wearing long-sleeved clothing and performing regular tick checks. The ticks can be as small as a poppy seed. One way to spot them is by looking for a tiny, shiny freckle.
With new vaccines in development, there is hope for more effective prevention. The vaccine candidate VLA15, developed by Valneva and Pfizer, is in a late-phase clinical trial and is being tested in large groups of people. If the results are successful, the next step is for the vaccine to be approved by the FDA. VLA15 was built to target the outer surface protein of the Borrelia burgdorferi bacteria, called OspA. OspA is produced primarily by the bacteria when they are in the tick. Blocking OspA would stop the bacteria from leaving the tick and infecting humans.
“When a tick feeds on a vaccinated individual, the antibodies and other compounds in the person’s blood kill the bacteria while they are still in the tick,” Dr. Coburn said. “Since bacteria in different regions of the world produce different versions OspA, this vaccine has been engineered to link multiple versions of OspA together.”
The VLA15 vaccine candidate is a different composition than the previously available human vaccine for Lyme disease, LYMERix®, which was discontinued by the manufacturer in 2002. The company voluntarily discontinued it due to a lack of interest (Lyme disease case numbers at the time were lower) and fears of arthritis as a vaccine side effect. The manufacturers of VLA15 changed the portion of the bacterial protein that was thought to be potentially responsible for arthritis in their product.
Second Lyme Disease Vaccine and Monoclonal Antibody Injection in Development
A second Lyme disease vaccine is in the early stages of development at the Yale School of Medicine. This vaccine candidate is intended to work by activating an immune response in the body when it recognizes tick saliva. The immune response is triggered at the site of the bite before the bacterium can be transmitted from the tick. A vaccine against tick saliva could also prevent transmission of other infections transmitted by these ticks.
A monoclonal antibody against Lyme disease is also in the early phases of development. Researchers at the University of Massachusetts Chan Medical School are working on a single injection that would be delivered at the start of peak tick season to provide seasonal protection against Lyme disease. The monoclonal antibody, called Lyme PrEP, works by a process called passive immunization, which is a mechanism that is different from vaccines. Lyme PrEP delivers a single, human anti-Lyme blood protein directly to a person rather than triggering the person’s immune system to fight off infection. So far, it has been studied in animals and was effective at blocking infection.