Lyme disease vaccine?
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Carl Karasti
Mar 31, 2026, 1:29:19 PM (5 days ago) Mar 31
to Ely Field Naturalists
Below is the news about a possible Lyme disease vaccine, taken from the Your Local Epidemiologist newsletter. You can read the whole newsletter by following this Substack link and you can sign up to receive the newsletter emails.
Carl Karasti
A Lyme disease vaccine may finally be on the horizon
Ticks spread Lyme disease, one of the most common and debilitating infections in the country, and for the first time in over two decades, a vaccine to prevent it may finally be on the way. The only vaccine we had before, LYMErix, was pulled from the market in 2002. Not because it was unsafe (the FDA found no real problems) but because rumors about arthritis side effects, amplified by bad press and lawsuits, scared people.
Now Pfizer and French vaccine company Valneva have announced their new vaccine candidate worked in more than 70% of cases in a large late-stage trial of 9,400 people aged five and older.
Ticks spread Lyme disease, one of the most common and debilitating infections in the country, and for the first time in over two decades, a vaccine to prevent it may finally be on the way. The only vaccine we had before, LYMErix, was pulled from the market in 2002. Not because it was unsafe (the FDA found no real problems) but because rumors about arthritis side effects, amplified by bad press and lawsuits, scared people.
Now Pfizer and French vaccine company Valneva have announced their new vaccine candidate worked in more than 70% of cases in a large late-stage trial of 9,400 people aged five and older.
How does the Lyme disease vaccine work?
The vaccine works differently from most other vaccines in a very cool way. Instead of just protecting you, it actually works inside the tick:
The vaccine trains your body to make antibodies against a protein (called OspA) found on Lyme-causing bacteria.
When a tick bites you, it drinks your blood along with those antibodies.
The antibodies neutralize the bacteria in the tick’s gut, stopping it from ever reaching its salivary glands and getting into you.
But there are a few things worth understanding
The trial hit a statistical snag. The trial had fewer Lyme disease cases than expected, making the results too uncertain to be conclusive. Researchers had planned two ways to measure the vaccine’s effectiveness before the study began: one starting 28 days after the final dose, which fell just short of the required confidence threshold, and one starting the day after the final dose, which cleared it. Pfizer cited both results in deciding to seek regulatory approval.
The regulatory path is murky. The manufacturer will seek FDA approval, and if granted, the vaccine will go to ACIP for a policy recommendation. The problem: ACIP currently has no members. What happens next is genuinely unclear.
The bigger question is whether people will actually use it. The vaccine requires four doses over about a year, plus what looks like an annual booster before tick season. That’s a real commitment. Lyme disease is far better known today than it was in 2002, which gives people more reason to seek protection. But wanting a vaccine and completing every dose are two very different things.
The trial hit a statistical snag. The trial had fewer Lyme disease cases than expected, making the results too uncertain to be conclusive. Researchers had planned two ways to measure the vaccine’s effectiveness before the study began: one starting 28 days after the final dose, which fell just short of the required confidence threshold, and one starting the day after the final dose, which cleared it. Pfizer cited both results in deciding to seek regulatory approval.
The regulatory path is murky. The manufacturer will seek FDA approval, and if granted, the vaccine will go to ACIP for a policy recommendation. The problem: ACIP currently has no members. What happens next is genuinely unclear.
The bigger question is whether people will actually use it. The vaccine requires four doses over about a year, plus what looks like an annual booster before tick season. That’s a real commitment. Lyme disease is far better known today than it was in 2002, which gives people more reason to seek protection. But wanting a vaccine and completing every dose are two very different things.
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