Pfizer and Valneva announced that their Lyme disease vaccine, made up of six strains, demonstrates 70% to 73% effectiveness in preventing it in people five years and older. However, the statistical target was not met due to a lower number of Lyme cases during the trial.
The vaccine, developed in areas with high incidence of the disease in the US, Canada and Europe, has shown encouraging results. Pfizer has stated that the reduction in infections is clinically significant and is projected to be submitted for regulatory approval, which would mark the return of the first vaccine available for humans against Lyme in more than 20 years.
With approximately 476,000 diagnoses annually in the US, Lyme disease is the most common vector-borne disease in the Northern Hemisphere. It is important to address this problem, since not detecting it can cause serious long-term health complications.
How the new vaccine works
Known as PF-07307405 (LB6V), the vaccine is multivalent and acts on the OspA protein of the Borrelia burgdorferi bacteria. When vaccinated, the body generates antibodies that the ticks ingest when feeding, preventing the bacteria from entering the bloodstream.
However, the history of the LYMERix vaccine, which was withdrawn from the market due to concerns about adverse effects in 2002, may influence public perception of the new option. Growing distrust of vaccines, exacerbated by anti-vaccine movements, could present additional challenges to their acceptance.
According to the Centers for Disease Control and Prevention (CDC), symptoms include fever, headache, fatigue, and a skin rash called erythema migrans. If left untreated, the infection can spread to the joints, heart, and nervous system.
Early localized stage
- They appear days or weeks after the bite and include fever, chills, headache, fatigue, muscle and joint pain, and neck stiffness.
- The most characteristic symptom is erythema migrans, a red “bull’s eye”-shaped rash that expands and is not itchy or painful, present in up to 80% of cases.
Early disseminated stage
- If left untreated, the infection spreads and can cause additional rashes, facial paralysis, severe pain in large joints such as the knees, heart palpitations, and neurological problems such as numbness or tingling.
Late stage
- Months or years later, chronic arthritis with swelling, intermittent tendon and bone pain, brain or spinal inflammation, and memory or vision problems arise.
Affectation by age groups and health conditions
Lyme disease, caused by the bacteria Borrelia burgdorferi and transmitted by ticks, affects variably depending on age and pre-existing health conditions, with higher risks of complications in vulnerable groups.
Children. Children, especially younger ones, usually present with acute arthritis with a single episode, while in adolescents it can become more chronic and recurrent. They are more susceptible to serious symptoms such as fatigue and joint pain if not treated early. At this stage, the child’s immune system responds well to antibiotics, but delay in diagnosis can lead to neurological or cardiac problems.
Older adults. Older adults face more intense symptoms, such as severe arthritis, chronic fatigue, and “brain fog” (cognitive difficulties), due to a weakened immune system. They are at higher risk of late spread with prolonged joint pain and cardiac complications.
Young and middle-aged adults. In adult men, more active outdoors, early spread with multiple rashes, facial paralysis, or Lyme carditis is common. Women may experience similar symptoms, but with a lower incidence.
Pre-existing conditions. People with immunosuppression or chronic diseases (such as rheumatoid arthritis or HIV) develop serious complications more quickly, including meningitis, persistent neurological problems, and put-up-Lyme syndrome with fatigue and insomnia. Risk increases by interaction with underlying conditions.
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