Major test of first possible Lyme vaccine in 20 years begins

DUNCANSVILLE, Pa. — Researchers are seeking thousands of volunteers in the United States and Europe to test the first potential vaccine against Lyme disease in 20 years — in hopes of better fighting the tick-borne threat.

Lyme is a growing problem, with cases rising and warming weather helping ticks expand their habitat. In Iowa, the number of confirmed and suspected cases has been heading upward, reaching a combined total of 356 cases in 2021 — the highest number in at least 12 years, according to state health officials. Most of the cases in Iowa are on the eastern side of the state, with Johnson County having the state’s fifth highest per capita incidence rate.

While a vaccine for dogs has long been available, the only Lyme vaccine for humans was pulled from the U.S. market in 2002 because of a lack of demand, leaving people to rely on bug spray and tick checks instead.

Now Pfizer and French biotech Valneva are aiming to avoid previous pitfalls in developing a new vaccine to protect both adults and kids as young as 5 from the most common Lyme strains.

"There wasn't such a recognition, I think, of the severity of Lyme disease" and how many people it affects the last time around, Pfizer vaccine chief Annaliesa Anderson told the Associated Press.

Robert Terwilliger, an avid hunter and hiker, was first in line Friday when the study opened in central Pennsylvania. He's seen lots of friends get Lyme and is tired of wondering if his next tick bite will make him sick.

"It's always a worry, you know? Especially when you're sitting in a tree stand hunting and you feel something crawling on you," said Terwilliger, 60, of Williamsburg, Pa.

Exactly how often Lyme disease strikes isn't clear. The Centers for Disease Control and Prevention cites insurance records suggesting 476,000 people are treated for Lyme in the nation each year. Pfizer's Anderson put Europe's yearly infections at about 130,000.

Black-legged ticks, also called deer ticks, carry Lyme-causing bacteria. The infection initially causes fatigue, fever and joint pain. Often — but not always — the first sign is a red, round bull's-eye rash.

Early antibiotic treatment is crucial, but it can be hard for people to tell if they were bitten by ticks, some as small as a pin. Untreated Lyme can cause severe arthritis and damage the heart and nervous system. Some people have lingering symptoms after treatment.

Most vaccines against other diseases work after people are exposed to a germ. The Lyme vaccine offers a different strategy working a step earlier to block a tick bite from transmitting the infection, said Dr. Gary Wormser, a Lyme expert at New York Medical College who isn't involved with the new research.

How? It targets an "outer surface protein" of the Lyme bacterium called OspA that's present in the tick's gut. It's estimated a tick must feed on someone for about 36 hours before the bacteria spreads to its victim. That delay gives time for antibodies the tick ingests from a vaccinated person's blood to attack the germs.

In small, early-stage studies, Pfizer and Valneva reported no safety problems and a good immune response. The newest study will test if the vaccine, called VLA15, really protects and is safe. The companies aim to recruit at least 6,000 people in Lyme-prone areas.

They'll receive three shots, either the vaccine or a placebo, between now and next spring's tick season. A year later, they'll get a single booster dose.

"We're really looking at something that's a seasonal vaccine," Anderson said, so people have high antibody levels during the months when ticks are most active.

Volunteers can be as young as 5 and should be at high risk because they spend a lot of time in tick-infested areas, such as hikers, campers and hunters, said Dr. Alan Kivitz who heads one of the study sites at Altoona Center for Clinical Research in Duncansville, Pa.

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute's Department of Science Education. The AP is solely responsible for all content.