A new Lyme disease vaccine is closer to approval. Here's what to know.

The pharmaceutical companies testing out a new Lyme disease vaccine said Monday they plan to seek approvals from the federal government even though the latest clinical trial results were not as successful as they had hoped.

Long Island, with its bountiful tick population, has been a hot spot for Lyme disease, the most common tick-borne illness in the nation. Suffolk County had the highest number of Lyme disease cases in the state in 2024.

This is the first time in more than a decade that a Lyme disease vaccine could be rolled out to the public. The vaccine was developed by Manhattan-based Pfizer Inc. and Valneva SE, which is based in France. It is designed for people 5 years old and up.

The companies said the vaccine was 73% effective in reducing the rate of Lyme disease 28 days after the fourth dose and 75% effective in reducing that rate one day after the fourth dose.

But in a statement, Pfizer said “fewer than anticipated" Lyme disease cases were reported over the study period and a statistical criterion was not met.

Instead of hitting their goal of showing the vaccine had a 95% to 20% “confidence interval,” or effective rate, it resulted in 95% to almost 16%.

Pfizer said other trials have met the 20% threshold and it is “confident in the vaccine’s potential and is planning submissions to regulatory authorities.”

Lyme disease is caused by the bite of an infected blacklegged tick. Not all blacklegged ticks carry the disease, which results in a bacterial infection. Symptoms include fever, headache, fatigue and a rash that sometimes takes the form of a bullseye.

If caught in time, it can be treated with antibiotics.

In more serious cases, Lyme disease can cause joint pain, arthritis and facial paralysis

“I think considering how large a problem Lyme disease is in New York, having a safe and effective vaccine in our toolbox would be wonderful,” said Dr. Andrew Handel, a pediatric infectious disease specialist at Stony Brook Children’s Hospital who has a focus on tick-borne illnesses.

“Avoiding tick bites is part of daily life here on Long Island,” Handel said. “And even though New York is absolutely a leader in Lyme disease public health awareness and educational outreach, taking preventative measures is not always enough to avoid these infections.”

Stony Brook University participated in the early phases of the clinical trial for the Lyme vaccine.

The Centers for Disease Control and Prevention said over 89,000 cases of Lyme disease were reported in 2023, the most recent numbers available. They said some estimates show the actual number of people diagnosed and treated may be closer to 476,000.

In New York State, 21,632 cases of Lyme disease were reported in 2024. The highest number of cases was found in Suffolk, with 3,152. Nassau reported 521 cases.

Handel said it may not be clear how effective the vaccine is until there are larger studies or it comes to market and people start using it.

In the late 1990s, a vaccine called LYMErix was released but was pulled later because the manufacturer said there was not enough interest. Some people had complained about side effects, but the Food and Drug Administration determined the vaccine was not the cause of any injuries people may have suffered.

Awareness and reporting of Lyme disease have grown significantly since that time. In December, U.S. Health and Human Services Secretary Robert F. Kennedy Jr. pledged to focus federal attention and resources on the disease. During his 2025 confirmation hearings, Kennedy said he would work hard for treatments or vaccines for Lyme disease.

By Lisa L. Colangelo

lisa.colangelo@newsday.com@lisalcolangelo

Lisa joined Newsday as a staff writer in 2019. She previously worked at amNewYork, the New York Daily News and the Asbury Park Press covering politics, government and general assignment.