In Canada, reported cases of Lyme disease have surged from just 144 in 2009 to 5,809 in 2024, with preliminary figures for 2025 reaching 7,105. This increase is attributed to the spread of blacklegged ticks carrying the bacterium Borrelia burgdorferi, which can lead to serious health complications if untreated. Although a vaccine for Lyme disease in humans, LYMErix, was withdrawn in 2002 due to safety concerns and declining demand, two new vaccines are under development. Pfizer and Valneva have completed Phase 3 clinical trials for a vaccine named PF-07307405, showing over 70% efficacy. Meanwhile, Moderna is working on two mRNA-based vaccines currently in Phase 2 trials. The urgency for a Lyme disease vaccine is underscored by the rising case numbers and the potential for severe health impacts from the infection.
Why It Matters
The significant rise in Lyme disease cases in Canada reflects broader trends in tick-borne illnesses linked to climate change, habitat expansion, and increased human exposure to ticks. The absence of an approved human vaccine since LYMErix was withdrawn underscores the challenges in vaccine development and public health communication. As Lyme disease continues to pose a growing health risk, the progress of new vaccines could play a crucial role in prevention efforts, particularly given the disease’s potential long-term health complications. Access to effective vaccination could significantly reduce incidence rates and improve public health outcomes as tick populations expand across Canada.
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