Only a Lyme disease vaccine in development goes to Phase 3 trials

Participants will receive three doses of the vaccine, called VLA15, or a placebo, followed by a booster dose.

“With global rates of Lyme disease increasing, providing people with a new option to help protect themselves from the disease is more important than ever,” said Annalisa Anderson, senior vice president and chief of vaccine research and development at Pfizer, in the press release. .

Pfizer said in its statement that the Lyme vaccine is the only Lyme vaccine in clinical development. It targets the bacterium Borrelia bordorferi, the main cause of tick-borne disease, and has “shown a robust immune response and a satisfactory safety profile in preclinical and clinical studies to date.”

If the trial shows the vaccine is safe and effective, Pfizer says, it could file applications for approval from the U.S. Food and Drug Administration and the European Medicines Agency in 2025.

What is Lyme disease?

Lyme disease is the most common vector-borne disease in the United States, according to the U.S. Centers for Disease Control and Prevention, and it’s becoming common in more areas.

An estimated 476,000 Americans are diagnosed and treated for Lyme disease each year, although the CDC says this may be an overrun because people are sometimes treated without official confirmation that they have the disease.

The only vaccine previously marketed in the United States was discontinued in 2002.

Lyme disease symptoms

Fever, chills, body aches, swollen lymph nodes, a stiff neck, shortness of breath, headache, fatigue, and a rash are all typical symptoms of Lyme disease.

When you are bitten by a tick, you will usually see a small red bump that may look like a mosquito bite. But after three to 30 days, if a rash appears and expands from that red area and looks like a bull’s-eye, that’s a sign that you may have Lyme disease.

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Doctors will call this rash erythema migrans. Oftentimes, it will expand slowly. It does not usually cause itching or pain, but the area may feel warm to the touch.

Between 70% and 80% of people with Lyme disease develop this rash, and some develop it in more than one place on their body.

If left untreated, the infection can spread to the joints, heart, and nervous system, according to the CDC. This can lead to joint pain and swelling.

After several weeks to months, there may also be swelling of the membranes surrounding the brain, temporary paralysis of one side of the face and ‘brain fog’: forgetfulness or confusion.

How do people get Lyme disease?

Lyme disease comes from four main types of bacteria. In the United States, it is Borrelia burgdorferi. Sometimes, Borrelia mayonii can also cause disease, according to the CDC.
An infected tick transmits bacteria when it bites. There are several types of ticks in the United States that carry the bacteria that cause Lyme disease, and as temperatures rise, they can be found in nearly every county.
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Most commonly, the black tick, also known as the deer tick, carries Lyme disease. They live in the northeastern United States and in the mid-Atlantic and upper Midwest. The western black tick that carries Lyme disease can be found along the Pacific coast.

Most people get Lyme disease in the spring and summer. This is the time when immature ticks called nymphs feed, and that’s when most people are outside, walking through grass and densely wooded areas where the bugs like to hang out.

What do you do if you get bitten?

Ticks can be small: Deer ticks may be as small as a pinhead, so look for them carefully.

Removing the tick within 24 hours reduces the risk of developing Lyme disease. The longer the tick is attached to the body, the more likely this person will be infected. Use the forceps to carefully and steadily pull out the tick, holding it close to its mouth or neck. Then put the cleanser on the affected area.

The bacteria usually takes about 36 to 48 hours to pass from the tick to the person it sticks to, according to the CDC.

If you are bitten and develop symptoms, contact your doctor immediately. Even if the symptoms are gone, you should still see a doctor.

Lyme disease treatment

The standard treatment for early-stage Lyme disease is the use of oral antibiotics. Usually, a 14- to 21-day course is recommended, but some studies suggest that a 10- to 14-day course is equally effective, according to the Mayo Clinic.

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If the central nervous system is affected by the disease, intravenous antibiotics may be given for 14 to 28 days. This treatment kills the infection, but you may need more time to recover from symptoms. Side effects of this treatment may include low white blood cell count, diarrhea, or infection with other antibiotic-resistant organisms unrelated to Lyme disease.

People who take antibiotics early in the disease make a full recovery, according to the Mayo Clinic. Patients who receive treatment later for infection may take longer to respond to treatment.

Most people recover fully, regardless of when they get help, but about 5% to 20% have persistent symptoms, and some can be disabled.


The Centers for Disease Control and Prevention (CDC) recommends wearing insect repellents with at least 20% DEET concentration and avoiding wooded areas with high grass, where ticks are most often found.

Check for ticks daily, and if you spend a lot of time outdoors, shower frequently. A piece of cloth can help remove non-adherent ticks.

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When you’re out and about, cover up. Wear long sleeves, long pants, and hats when hiking or hiking in the woods.

Dogs and cats can also bring pests indoors, so check them out and park your garden. Wipe the sheets and brush where you want to hide the tick. Keep your garden mowed.

More facts about ticks

These spiders cannot fly or jump but rather wait for a host—whether a mammal, bird, reptile, or amphibian—to feed while resting on the edges of weeds and shrubs. They cling to leaves and grass with their lower legs, a pose called “striving.”

When the host passes, the tick climbs up and finds a place to bite.

Besides Lyme disease, at least 20 known medical conditions can result from tick bites.

CNN’s Elizabeth Landau contributed to this report.

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