How big is the Lyme disease problem?
In the Netherlands alone it is number of patients quadrupled in twenty years. Elsewhere, too, the number of patients is increasing rapidly. Success is therefore essential in combating the disease.
How does Lyme disease develop?
The disease is caused by the Borrelia bacteria that ticks sometimes carry in their gastrointestinal tract. After a tick bite, the bacteria can spread through the bloodstream and cause symptoms of disease. Every year in the Netherlands about 1.5 million people are bitten by a tick, of whom 27 thousand contract Lyme disease. according to the RIVM. Antibiotics are usually effective, but because not everyone immediately notices a tick bite, chronic health problems can arise. This happens to 1,000 to 2,500 people every year. They suffer from fatigue and complaints of the heart or nervous system.
Can’t you prevent a tick bite by paying close attention?
Wearing long sleeves and long pants when going out into nature and checking yourself regularly for tick bites: these are the advice given by health authorities around the world. But the question is whether they help.
American epidemiologists who have analyzed all studies into the effect of those advices wrote last month in the magazine Zoonoses and Public Health that there is very limited evidence that they can prevent Lyme. Now that the number of ticks is rising rapidly due to climate change and the number of cases of disease is increasing, just paying close attention is no longer sufficient.
If there are so many infections, why is there still no vaccine?
A vaccine was once available in the United States, but it was withdrawn from the market in 2002 after patients sued the pharmaceutical company for serious side effects. The vaccine, LYMErix, is said to have caused joint inflammation in a number of patients. The FDA, the US drug agency, found no evidence for thisbut by then the vaccine had already fallen out of favor.
The new vaccine, currently known under the working title VLA15, has been proven in research in patients to be safe and has also been shown to elicit a strong immune response. Now a major study, in fifty hospitals, must show whether and how often the vaccine can prevent Lyme disease. Pfizer is collaborating with the French biotech company Valneva on this. Six thousand test subjects are taking part from countries where Lyme disease is common, such as the United States, Germany, Poland and the Netherlands.
How does that new vaccine work?
The vaccine stimulates the immune system to produce antibodies against a protein on the outside of the Borrelia bacteria, says internist-infectiologist Michelle Klouwens, who is involved in international vaccine research at Amsterdam UMC. When people come into contact with the harmful bacteria later, their immune system is trained and antibodies are available at lightning speed. They prevent the bacteria from spreading through the bloodstream.
It is still unclear whether people are protected forever by this, says Klouwens. The research should prove that. The participants receive a vaccine three times in nine months and a booster after one year. They are then followed for a longer period of time.
Is there a need for a vaccine? Of all people who are bitten by a tick, only two in a hundred contract Lyme, so who is vaccinated four times?
‘Perhaps the vaccine is not immediately interesting for the average Dutch person,’ says Klouwens, ‘but it is for the group of people who are often in nature because of their work or hobby.’ Especially now that the number of annual tick bites is rising, an effective means of prevention can be important for them, she thinks. The Amsterdam UMC is looking for nature lovers who get a tick bite at least once a year and who want to participate in the study. Vaccinations will start in September, says Klouwens, so that the first measurements of effectiveness can take place in the next tick season, in the spring and summer of 2023.
If the results of the international study are favourable, pharmaceutical company Pfizer hopes to submit the vaccine to the drug authorities for approval in three years’ time.