Lyme Disease: The Disease & Vaccine

Lyme Disease: The Disease & Vaccine

In the early 1970s, a group of children in Connecticut developed symptoms suggestive of juvenile rheumatoid arthritis. But, because the cases were clustered in time and geographic region, and because some features were distinct from juvenile rheumatoid arthritis, including an unusual skin lesion, a group of healthcare providers in the area studied the cases more closely. In 1977, they published their findings, indicating that these cases represented a new disease. The cases occurred in and around Old Lyme, Connecticut. The new disease became known as Lyme disease.

Lyme disease is caused by bacteria in the Borrelia species. Borrelia is spread through the bite of an infected tick. In the U.S., Lyme disease is most commonly found in the Northeast, mid-Atlantic, and Midwest regions. Lyme disease also occurs in other parts of the world, including in Scandinavia and central Europe, Russia, China, and Japan. Each year in the U.S., close to 500,000 people are diagnosed with and treated for Lyme disease. Most people recover completely from Lyme disease if they receive antibiotic treatment; however, some people may experience lingering symptoms after completing treatment. A few people also experience severe disease before beginning treatment. 

The disease

What is Lyme disease and how do you catch it?

Lyme disease is caused by infection with a bacterium called Borrelia burgdorferi. Most often, Borrelia bacteria infect small mammals (e.g., mice, chipmunks, hedgehogs, squirrels) and birds, but the bacteria can infect other mammals as well. Ticks become infected with the bacteria when they feed on the blood of infected animals. Once infected, they spread the infection to other organisms, including humans, during blood meals. Only infected ticks can spread Lyme disease. It has not been shown to spread from person-to-person. 

For a person to develop Lyme disease following a tick bite, certain conditions need to be met. If these are not present, the person is unlikely to develop Lyme disease:

  • A tick must have been attached to a person’s body for at least 36 hours.
  • The tick must be of the type that carries Borrelia bacteria.
  • The individual tick must actually have Borrelia bacteria.

If a person is likely to have been exposed based on where they are located, the type of tick, and the length of exposure to the tick, they may be prescribed antibiotics. However, antibiotics should be started within 72 hours of the tick being removed in order to have the best chance of stopping the infection.

If a person does not live in, or has not recently frequented, an area where infected ticks are common, they are unlikely to develop Lyme disease. For more information on how Lyme disease is often misdiagnosed, check this article from Dr. Andrea Love in her Immunologic newsletter. 

When someone develops Lyme disease, it usually progresses across two stages with different symptoms during each stage. 

Stage 1

In the first stage of disease, 70 to 80 of 100 people experience a rash at the site of the tick bite. The rash is often described as looking like a “bull’s eye” or target that expands outward slowly over time. It can become quite large — even as large as 12 inches in diameter or more. The rash usually appears between 3 days and 1 month after exposure to the infected tick. People with the rash indicative of Lyme disease may be prescribed antibiotics.

Stage 2

During the second stage, the Borrelia bacteria spread throughout the body over several days to weeks. Symptoms of the second stage may include:

  • Fatigue
  • Headache
  • Fever
  • Neck pain, muscle pain and joint pain
  • Swollen lymph nodes
  • Additional bull’s eye or target-like lesions
  • Inflammation of the heart
  • Neurologic disease, including partial facial paralysis or weakness, meningitis (inflammation of the lining of the brain), or radiculoneuritis (inflammation of the nerves at the base of the spinal cord)

About 60 of 100 people who are not treated for Lyme disease will develop arthritis in one or more large joints (e.g., knee) within weeks to months of infection. In untreated people, the arthritis may take years to resolve. 

Most people recover from Lyme disease after being treated for 2 to 4 weeks with oral antibiotics. Even after treatment, some people will experience prolonged symptoms, including fatigue, body aches, or difficulty thinking. These prolonged symptoms are referred to as post-treatment Lyme disease syndrome (PTLDS). Its cause is currently unknown, but similar symptoms have been reported following viral infections, including SARS-CoV-2, Ebola virus, and dengue virus. People with PTLDS may be able to be treated for specific symptoms to be more comfortable, but no specific treatment is available for the overarching condition.

The vaccine

Currently, no vaccines are available to prevent Lyme disease in the U.S. In 1998, a Lyme disease vaccine, LYMERix, was approved for use in the U.S. While the vaccine was safe and effective at preventing Lyme disease, people had concerns about its safety and the vaccine was not recommended for large groups of people. As such, the company stopped making it in 2002. 

Clinical trials for new Lyme disease vaccines are underway. The candidate vaccine that will hopefully be approved in the near future is one that uses a surface protein from the Borrelia bacteria. This vaccine was created to protect against multiple strains of the bacteria that cause Lyme disease. 

How is the Lyme disease vaccine made?

The candidate vaccine is made using a Borrelia surface protein, called outer surface protein A or OspA. As several types of Borrelia bacteria can cause Lyme disease in the U.S. and Europe, scientists included the gene, or blueprint, from the six most common types that cause Lyme disease. The gene for each was put into a type of harmless bacteria, so that as the bacteria divide, they also produce the Borrelia OspA proteins. The bacteria are then killed and the six OspA proteins are purified. The six types of purified OspA are mixed in equal amounts to make the vaccine. During the clinical trials, the vaccine has been given as a series of four or five shots to determine which provides better immunity. People who got four shots, received the second one 6 months after the first. Two additional doses were given at 18 and 30 months. People who got five shots, got dose two 2 months after dose one, then they got three additional doses at 6 months, 18 months, and 30 months. 

Does the Lyme disease vaccine work?

The clinical trials determined whether vaccinated individuals developed immunity to the bacteria. The candidate vaccine was tested in healthy people between 5 and 65 years of age. After receiving four or five doses over 30 months, 9 of 10 recipients developed immune responses against Borrelia. However, this vaccine is still being evaluated in clinical trials, so no Lyme vaccine is currently available in the U.S.

Does the Lyme disease vaccine have side effects?

People who got vaccinated during the clinical trials experienced minor side effects, like pain or tenderness at the injection site, fatigue or headache. No serious side effects were identified. Larger clinical trials are ongoing and will provide additional information on the safety of the vaccine, including more rare side effects. 

Other questions you might have

I heard there are different types of bacteria that cause Lyme disease. Does the vaccine protect against multiple types of bacteria?

Lyme disease is caused by bacteria in the genus Borrelia. In the U.S., most cases of Lyme disease are caused by Borrelia burgdorferi sensu stricto. In other areas, Lyme disease is caused by other types of Borrelia. The candidate vaccine currently in late-stage clinical trials includes the Osp A proteins from the six most common types that cause Lyme disease in North America and Europe. 

Do the Lyme tests that I can get without a prescription work?

Generally, this answer is no. The only Lyme tests that are FDA-approved are those administered by healthcare providers. Unfortunately, some people take advantage of the confusion about this illness to profit by promoting Lyme disease diagnostics and treatments that have not been proven to work. Check out more in this article, “Lyme Disease: Fraudulent Tests Are Rampant,” by Dr. Andrea Love, a scientist who studied Lyme disease during college and in graduate school. 

If I get Lyme disease, will I develop chronic Lyme disease?

Lyme disease can be successfully treated with antibiotics and most people fully recover. A small group of people may experience lasting symptoms, such as fatigue, body aches, or difficulty thinking, even after they have received treatment. Post-treatment Lyme disease syndrome (PTLDS) is a more accurate description since “chronic Lyme disease” implies that a person’s prolonged symptoms are caused by an ongoing Borrelia infection. Currently, the cause of PTLDS is not known; however, studies have shown that prolonged use of antibiotics does not improve PTLDS symptoms and can cause serious complications. If you are experiencing PTLDS symptoms, talk with your healthcare provider or with an immunologist or infectious diseases specialist at an academic medical center (a hospital associated with a university) to sort out whether your symptoms are the result of PTLDS or if something else is happening. 

If I find a tick on me, should I immediately start taking antibiotics?

If the tick is not attached, antibiotics are not needed. For a tick to cause Lyme disease, it must be attached for at least 36 hours, be a type of tick capable of transmitting Borrelia bacteria and be infected with Borrelia bacteria. If the tick was attached for less than 36 hours, no action is needed beyond removing the tick and cleaning the bite. If the tick was attached for 36 hours or if it isn’t clear how long the tick was attached, seek medical attention. Healthcare providers may ask about the type of tick that was attached and where it was acquired to determine if it was a tick capable of transmitting Lyme disease. Once the healthcare provider has the information they need, they will determine whether antibiotic treatment is appropriate for your situation. 

Relative risks and benefits

Do the benefits of the Lyme disease vaccine outweigh the risks?

Each year, almost 500,000 people in the U.S. are treated for Lyme disease. The disease can cause severe symptoms, including neurologic symptoms, and if left untreated, it may result in lasting joint pain. Even after treatment, some people experience lingering symptoms that can take years to resolve. Currently, the U.S. does not have a vaccine for Lyme disease, but a candidate vaccine is in clinical trials.

Disease risks

  • Inflammation of the heart
  • Neurologic disease, including partial facial paralysis or weakness, meningitis (inflammation of the lining of the brain), or radiculoneuritis (inflammation of the nerves at the base of the spinal cord)
  • Lasting joint pain
  • Post-treatment Lyme disease syndrome (PTLDS), which may include prolonged symptoms such as fatigue, body aches, or difficulty thinking

Vaccine risks

  • A Lyme vaccine is not currently available in the U.S.

Reference

 

Reviewed by Paul A. Offit, MD, on Aug. 21, 2025