The incidence of Lyme disease in England has increased by over 20% in the last year, according to public health officials, as pharmaceutical companies intensify efforts to develop new vaccines and treatments for this tick-borne ailment.
The UK Health Security Agency (UKHSA) has reported in its One Health vector-borne disease surveillance report that there were 1,168 confirmed laboratory cases of Lyme disease in 2025. This marks a 22% rise from the 959 cases documented in 2024. Interestingly, the numbers are comparable to 2023, which saw 1,151 confirmed cases.
In addition to Lyme disease, two probable cases of tick-borne encephalitis complex were reported in 2025, increasing the total number of locally acquired cases to six since the virus was first detected in the UK in 2019.
Dr. Claire Gordon, who leads the rare and imported pathogens laboratory at UKHSA, commented, “The rise in laboratory-confirmed acute cases of Lyme disease in 2025 compared to 2024 is anticipated due to variations in awareness, testing rates, and factors influencing outdoor activities, such as weather. Overall trends for 2025 remain stable.”
Lyme disease is attributed to the bacterium Borrelia burgdorferi, which resides in the guts of ticks. These tiny, spider-like creatures inhabit grassy and wooded areas and feed on the blood of birds and mammals, including humans.
Dr. Gordon added, “The geographical spread of ticks in the UK has been expanding in recent years. However, tick populations continue to fluctuate due to weather changes, climate trends, habitat alterations, and shifting host populations.”
Symptoms of Lyme can include a bullseye-like rash, fever, muscle and joint pain, and lethargy. Left untreated, the condition can become chronic and, even among those who receive antibiotics, some report ongoing symptoms.
Not all ticks carry Lyme bacteria, and it is thought rapid removal of ticks reduces the risk of infection after a bite. But while there are various medications available to protect pets from Lyme disease – including monthly oral tablets and vaccinations – advice for humans centres on prevention, such as using repellants, covering exposed skin outdoors and wearing light-coloured clothing to make ticks easier to spot.
Linden Hu, a professor of immunology at Tufts medical school, said there were a number of reasons veterinary and human approaches differed, noting that pet owners were often more willing to medicate their dogs than themselves or family members, while clinical trials in humans were harder to conduct.
“It’s easier to do studies in animals because you can control the situation. You can put infected ticks on them to test if it’s going to work, which you really can’t do with humans,” he said, adding real-world studies, or “field trials”, were expensive and risky, given that it was unclear how many cases of Lyme would occur.
A vaccine against Lyme for humans, known as LYMErix, was previously available in the US, with trials suggesting it had an efficacy of 76% after a third dose. However, it was withdrawn from the market in 2002 after poor uptake.
“There were a couple of things that coalesced to cause the low sales,” Hu said, noting this included the US Centers for Disease Control and Prevention recommending it only for people at high risk of Lyme disease. There were also concerns the vaccine may be linked to arthritis. While evidence remained lacking, the negative media coverage and lack of trust in the vaccine contributed to low demand.
Several new treatments are in the works, including an mRNA vaccine from Moderna – a jab Hu has worked on that is in phase 2 of its clinical development – as well as a different vaccine from Pfizer and Valneva.
Crucially, Hu said, both approaches aimed to avoid activating the immune pathway some researchers suspected caused arthritis in certain recipients of LYMErix.
Not that it has been plain sailing. In the case of the Pfizer/Valneva vaccine, there were fewer than expected cases of Lyme among participants in a phase 3 trial, meaning that while the vaccine appeared to have an efficacy of more than 70%, the results were not as statistically robust as hoped. Despite this, the vaccine is to be submitted to regulatory authorities.
Other approaches are also being explored. Among them is monoclonal antibody from Tonix Pharmaceuticals, which could be given before exposure to ticks, while Hu is working on a drug with Tarsus Pharmaceuticals that is already used to protect dogs and cats. Unlike the vaccines, this drug – known as lotilaner – kills the ticks, rather than the bacteria they carry.
According to Hu, lotilaner works rapidly by killing the ticks before they have a chance to transmit Lyme or, potentially, other diseases.
Julia Knight, of the charity Lyme Disease UK, said it was unclear whether a vaccine would be adopted in the UK, given that figures for Lyme disease appeared to be low, although were likely higher – not least because they do not include the roughly 70% of people with Lyme who develop the telltale rash, as these patients are treated immediately without laboratory tests, and Lyme disease can be missed or misdiagnosed.
“Obviously any advances in science that prevents Lyme disease is always welcome, but whether people will welcome a vaccine or not in the current climate of vaccine hesitancy remains to be seen,” she said.
