Researchers are seeking thousands of volunteers in the United States and Europe to participate in a test of the first potential vaccine against Lyme disease in 20 years – in hopes of better fighting the tick-borne threat.
Lyme disease is a growing problem, with cases rising and warming weather helping ticks expand their habitat. While a vaccine for dogs has long been available, the only Lyme vaccine for humans was removed from the US market in 2002 due to lack of demand, leaving people to rely on bug spray and physically checking for the presence of ticks.
Pfizer and French biotech firm Valneva are aiming to avoid previous pitfalls in developing a new vaccine to protect both adults and kids as young as five from the most common Lyme strains on two continents.
“There wasn’t such a recognition, I think, of the severity of Lyme disease” and how many people it affects, Pfizer’s vaccine chief Annaliesa Anderson told The Associated Press.
Robert Terwilliger, an avid hunter and hiker, was first in line on Friday when the study opened in central Pennsylvania. He’s seen lots of friends get Lyme disease 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, Pennsylvania. “You’ve got to be very, very cautious.”
Exactly how often Lyme disease strikes is not clear. The Centers for Disease Control and Prevention cites insurance records suggesting 476,000 people are treated for Lyme in the US 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, as some are as small as a pin. Untreated Lyme can cause severe arthritis and damage the heart and nervous system. Some people have lingering symptoms even after treatment.
Most vaccines against diseases work after people are exposed to a germ. The Lyme vaccine offers a different strategy by 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 is not involved with the new research.
How the vaccine works
How does the Lyme vaccine work? It targets an “outer surface protein” of the Lyme bacterium called OspA that is present in the tick’s gut. It is estimated that a tick must feed on someone for about 36 hours before the bacteria spreads to its victim. That delay in transmission gives time for antibodies that the tick ingests from a vaccinated person’s blood to attack the germs right at their source.
In small, early-stage studies, Pfizer and Valneva reported no safety problems and a good immune response from participants. The newest study will test if the vaccine, called VLA15, really protects and is safe for people. The companies aim to recruit at least 6,000 people in Lyme-prone areas including the northeast US plus Finland, Germany, the Netherlands, Poland and Sweden.
Volunteers will receive three shots, either the vaccine or a placebo, between now and next spring’s tick season. A year later, they will receive 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 five 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 the Altoona Center for Clinical Research in Duncansville, Pennsylvania.
In his own practice, “not a single day goes by that someone either has a concern about Lyme disease, could possibly have Lyme disease,” Kivitz said.
This new candidate is different from a previous Lyme vaccine that GlaxoSmithKline pulled off the market in 2002 amid controversy and low sales. With about 75 percent effectiveness, that old Lyme shot got a lukewarm endorsement from vaccine experts, it was not tested in children, and drew unsubstantiated reports of joint-related side effects.
While the new Pfizer-Valneva vaccine also targets the OspA protein, it is engineered somewhat differently than its predecessor and also targets six Lyme strains in the US and Europe instead of just one.
The Pfizer study will span two tick seasons to get answers – but it is not the only research into new ways to prevent Lyme. University of Massachusetts scientists are also working on a vaccine alternative, shots of pre-made Lyme-fighting antibodies.
And Yale University researchers are in the early stages of designing a vaccine that recognises a tick’s saliva – which in animal testing sparked a skin reaction that made it harder for ticks to hang on and feed.
Since different tick species carry many diseases other than Lyme, ultimately “we’re all hoping for a tick-bite prevention vaccine,” New York Medical College’s Wormser said.