Lyme Disease Vaccine Passes Stage Three Trials

A Lyme disease vaccine candidate developed by Pfizer and French pharmaceutical company Valneva SE could be available to the general public within two years, having finished Phase 3 trials last week.

The VLA15 vaccine is a three-shot series followed by a booster. It targets the bacteria, Borrelia burgdorferi, that causes Lyme disease, preventing it from transmitting from infected ticks.

The participants in the trial were people ages five and older who spent a lot of time outdoors in areas where Lyme disease is common. Participants received either three doses of VLA15 or a saline placebo. They were then monitored for Lyme exposure and will receive the final booster shot or placebo before the peak of Lyme season in 2025.

At present there have been no safety issues observed associated with the vaccine. An additional trial focused on participants ages 5-17 is underway to confirm its efficacy and safety in children.

What is Lyme disease?

Lyme disease is a tick-borne illness first identified in Lyme, Connecticut in 1982. The disease is normally transmitted by deer ticks, which are most common throughout the US northeast, mid-Atlantic, and upper midwest regions. Although the overwhelming majority of reported cases occur in these regions, cases have been reported in all 50 US states.

Map from the CDC showing the geographic spread of Lyme disease in blue.

The disease causes a host of symptoms, most commonly fever, chills, aches and pains, swollen lymph nodes, and the iconic “bullseye” rash at the site of the bite. If left untreated these symptoms can worsen, causing arthritis, heart palpitations, and other serious — and potentially chronic — symptoms. 

The current treatment for Lyme disease is typically a 10- to 14-day course of the antibiotic doxycycline. Side effects include headache, nausea, and increased sun sensitivity. 

How the bullseye rash appears commonly on black skin (left) and white skin (right).

If you find a deer tick on you that has been attached for two to three days and begin experiencing symptoms of Lyme, seek medical attention. 

Why the vaccine is important for thru-hikers?

Lyme is a frequent concern for thru-hikers, especially those on the AT. If left untreated, it can end a thru-hike and treatment and the side effects can interrupt one. 

Lyme disease is getting more common in the face of climate change. Some evidence suggests that milder winters cause fewer ticks to die off. This, coupled with increased human-animal interaction due to the loss of forest habitat, could be fueling the uptick in cases of Lyme. 

The availability of a vaccine to prevent Lyme disease would remove a common stressor for thru-hikers. 

What comes next?

Next in the trial comes a year of monitoring the participants until the end of Lyme disease season 2025. Following the submission of the vaccine to the Food and Drug Administration (FDA), the vaccine should be available in 2026. 

Until the vaccine is out, the best way to prevent Lyme disease is with regular tick checks. Check your whole body for ticks at the end of the night, during a midday break, or at some other predetermined time every day. If you find one that has attached, remove it by the head using tweezers or a tick key. 

Different tick removal devices: two different styles of tick keys and a pair of fine-pointed tweezers.

This prevents them from attaching for long enough to transmit Lyme. If you find one attached and are unsure how long it has been on you, place it in a plastic baggie and bring it with you to a medical professional. Some medical facilities will be able to test the tick for Borrelia burgdorferi on-site, potentially preventing a long course of antibiotics. 

To learn more about Lyme disease and how it affects thru-hikers, check out Backpacker Radio #200 | Lyme Disease Symptoms, Treatments, and Prevention with Dr. Brian Fallon and Noah Johnston.

Image by Erik Karits from Pixabay