London man among thousands who've rolled up their sleeves to trial Lyme disease vaccine

Working outdoors as a landscaper in the summer, Maxwell Dick is at a higher risk than most people of being bitten by a tick and developing a tick-borne disease.

The most prevalent of them, and the most common vector-borne disease in North America, is Lyme disease, which has seen case rates soar over the past decade. Despite that, and the potentially debilitating long-term symptoms that can result, including chronic fatigue, body aches and cognition issues, no preventable vaccine is currently available.

"There's a lot of people in my industry who get ticks all the time, and to prevent some Lyme disease would be wonderful," Dick said.

With that in mind, the London resident and Fanshawe College horticulture instructor signed up for a clinical study for a new, potential Lyme disease vaccine.

The clinical trial for the vaccine, VLA15, developed by Pfizer and Valneva, began in August 2022. Stage 3 trials got underway in late 2023 involving more than 9,000 participants from areas of Canada, Europe, and the U.S. where the disease is endemic. 

Dick says he signed up after seeing a form at his doctor's encouraging participants. "It literally was like, 'Are you a landscaper? Do you like being outdoors? Do you hike? Do you have pets?' I was like, yes to everything," he said.

Half of the participants receive three doses of VLA15, while the other half receive three doses of a placebo, both within the first year, followed by a booster a year later. Dick says he expects to find out what he was given in December or January.

"They called me (April 14) because I had gotten my blood taken for the last time a few weeks ago, and they were just checking in … It's funny, they're like, 'we don't want you to get a tick, but if you do, that'd be great,'" he said with a chuckle.

Pfizer and Valneva say they expect Stage 3 to finish by years-end, and in July said the vaccine had "shown a favourable safety profile across all dose and age groups" in all trials to date.

CBC News has reached out to Pfizer for comment.

Should the vaccine go to market, it would be the first in more than 20 years. LYMErix, a vaccine from SmithKline Beecham, now GSK plc, was approved in the late 1990s but pulled by the drugmaker in 2002.

In 2018, Sam Telford of the original research team blamed the decision on low sales revenue and a class action lawsuit alleging significant adverse reactions. The suit was settled in 2003, with no financial compensation awarded to claimants. 

The new vaccine is similar in that it also targets the same surface protein (OspA) of the spirochete bacterium that causes Lyme disease, said Dr. George Chaconas of the University of Calgary. There are some differences.

"If you get the vaccine, your body develops antibodies to OspA. When the tick takes a blood meal, along with the blood come your antibodies," which kill the bacteria while they're in the tick, he said. "The mechanism is quite cool."