When will a Lyme disease vaccine be available in Canada?

Wading through long grass has never felt so menacing. Tick bites are on the rise. The microscopic menace, commonly referred to as the black-legged tick or deer tick, are the main culprits in spreading Lyme disease, a bacterial infection that if left untreated can spiral into serious symptoms, such as facial palsy, swollen joints, and inflammation of the brain and spinal cord.

According to the Public Health Agency of Canada, the number of confirmed Lyme disease cases has risen from 144 in 2009 to 3,147 in 2021. Our neighbours to the south are seeing even more staggering numbers. The Center for Disease Control and Prevention (CDC) estimates that as many as 476,000 Americans are infected with Lyme disease each year.

Infected ticks are usually found in high grass or brush, and they spread the disease by attaching themselves to a person. The ticks then migrate to a hard-to-spot area, such as the groin, armpit, or scalp, and chomp down, transferring a bacterium known as Borrelia burgdorferi into the person’s blood stream. However, the tick must be attached for at least 36 hours for the bacterium to be transferred. And most Lyme disease cases can be cured by antibiotics. Although, even after treatment, some symptoms, such as pain, fatigue, and difficulty thinking can last as long as six months.

That’s why researchers are working on a way to cut out the antibiotic treatment, instead empowering the human body to kill off the bacterium before it takes root.

In April 2020, pharmaceutical companies Pfizer and Valneva partnered to develop a Lyme disease vaccine known as VLA15. The vaccine received a Fast Track Designation from the Food and Drug Administration (FDA) in the U.S., which is meant to expedite the review process.

The vaccine works by creating antibodies that block a protein known as OspA found in Borrelia burgdorferi. By blocking the protein, the bacterium is unable to leave the tick and infect humans.

In August 2022, the vaccine entered Phase 3 of clinical trials and was being tested on 6,000 participants five years of age and older. Participants were recruited from areas where Lyme disease is highly endemic, including Finland, Germany, the Netherlands, Poland, Sweden, and the U.S. By December, the trial had shown that the vaccine created effective antibodies that lingered for up to six months.

“Rates of Lyme disease continue to increase globally, underscoring the importance of a vaccine that may help protect both adults and children,” said Annaliesa Anderson, the senior vice president and the chief scientific officer of vaccine research and development at Pfizer in a statement. “These six-month antibody persistence data are encouraging.”

But the trial hit a snag in February. The two companies discovered that a third-party contractor had breached clinical trial guidelines, impacting collected data from close to half of the trial’s participants.

In a joint statement, the companies stressed that the participants’ safety was not at risk, but those affected by the breach would have to discontinue the trial. All other participants will continue being tested, and Pfizer said it will work to enroll new participants so that Phase 3 of the study can be completed. The companies are still optimistic that the FDA will approve the drug by 2025—and considering the FDA’s close partnership with Health Canada, it’s likely the vaccine would be approved in Canada soon after.

But the delay in its trials could prevent VLA15 from being the first Lyme disease treatment to market. A group in the MassBiologics department of the UMass Chan Medical School in the U.S. is working on its own cure, a shot known as Lyme PrEP.

The treatment is not a vaccine, explained Mark Klempner, a professor of medicine with MassBiologics, in a statement. Instead, it’s a pre-exposure prophylaxis, which prevents infection by delivering a single antibody to a person rather than triggering their immune system to make multiple antibodies, the way vaccines do. This antibody travels through a person’s blood into the tick’s gut where it kills the bacterium before it has the chance to travel to the person.

The researchers have wrapped up Phase 1 of Lyme PrEP’s trials, where 48 volunteers received the shot with the antibody lingering in their system for at least six months. If Phase 2 and 3 of the trials run smoothly, Klempner predicts that the shot could be commercialized by 2025.

In the meantime, to avoid contracting Lyme disease, Klempner suggests people check themselves for tick bites after walking through long grass and to clear brush and debris from their properties.

“Ticks don’t like open fields. They really are along the edges of properties and so to the extent that you can clean up the brush in your neighbourhood or in your area, you will reduce the chance of being exposed,” he said.