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. A group of healthcare providers in the area studied the cases more closely because of the clustering in time and geographic region and because some of the symptoms did not align with that condition. For example, the children had unusual skin lesions. By 1977, the doctors determined the illness to be a new disease. The new disease was called Lyme disease because the cases occurred near Old Lyme, Connecticut.

Bacteria in the Borrelia species cause Lyme disease. Infected ticks spread Borrelia when they bite someone. In the U.S., Lyme disease is most common 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. 

Cases of Lyme disease have been increasing in the U.S. over time. While fewer than 100,000 cases have been confirmed annually in recent years, these numbers are thought to be lower than what actually occur. Annual estimates are that close to 500,000 people are diagnosed with and treated for Lyme disease annually. Most people recover completely from Lyme disease if they receive antibiotic treatment; however, some people experience lingering symptoms after completing treatment. A few people also experience severe disease before beginning treatment. 
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The disease

What is Lyme disease and how do you catch it?

In the U.S., a bacterium called Borrelia burgdorferi is the most common cause of Lyme disease. Other types of Borrelia bacteria also spread this disease. Most often, Borrelia bacteria infect small mammals (e.g., mice, chipmunks, hedgehogs, squirrels) and birds, but the bacteria can infect other mammals as well. The bacteria infect ticks when ticks feed on the blood of infected animals. Once infected, the ticks spread the infection to other organisms, including humans, when they feed on the blood of those organisms. Lyme disease has only been found in people bitten by infected ticks. Infected people have not been shown to spread Lyme disease to other people. 

Importantly, not all people bitten by a tick will develop Lyme disease. A person will only develop Lyme disease following a tick bite if certain conditions are met:

  • 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 the geographic location where they are located, the type of tick that bit them, 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. 

Lyme disease 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 develop 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 and can become quite large. In some cases, the rash can be 12 or more inches wide. The rash usually appears between three days and one month after exposure to the infected tick. People with a rash that looks like 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 bitten by infected ticks but not treated for Lyme disease will develop arthritis in one or more large joints (e.g., knee) within weeks to months of infection. The arthritis that occurs in untreated people may take years to resolve. 

Most people recover from Lyme disease after two to four weeks of treatment with oral antibiotics. Some people will experience prolonged symptoms of fatigue, body aches, or difficulty thinking even after receiving treatment. 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. Symptoms of PTLDS may be able to be treated, 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. The vaccine was safe and effective at preventing Lyme disease, but people had concerns about its safety and the vaccine was not recommended for large groups of people. As such, it was not used by large numbers of people, and the company stopped making it in 2002. 

Clinical trials for new Lyme disease vaccines are underway. If the candidate vaccine is found to be safe and effective, hopefully it will be approved so people have an option for protecting themselves against Lyme disease in the near future. 

How is the Lyme disease vaccine made?

The candidate vaccine is made using a Borrelia surface protein, called outer surface protein A or OspA. Several types of Borrelia bacteria can cause Lyme disease in the U.S. and Europe, so 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: 

  • Four shots: After the first dose, additional doses were given at six months, 18 months and 30 months for a total of four doses.
  • Five shots: After the first dose, additional doses were given at two months, six months, 18 months and 30 months for a total of five doses. 

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 either 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
  • 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?

Not necessarily. People can experience the following:

  • 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?

No. 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 and be a type of tick capable of transmitting Borrelia bacteria. Likewise, the tick must actually be infected with Borrelia bacteria.

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, it’s estimated that 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) that can include prolonged symptoms such as fatigue, body aches, or difficulty thinking

Vaccine risks

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

References

 

Reviewed by Paul A. Offit, MD, on Jan. 24, 2026