Pfizer’s Lyme Vaccine Misses Mark in Study, Complicating Quest for Approval
Drugmaker seeking regulatory review for first new shot to combat disease in decades
- Pfizer and Valneva’s experimental Lyme disease vaccine was over 70% effective in a trial, but the findings were inconclusive due to low disease incidence.
- Valneva’s stock fell 39% on the uncertainty surrounding the vaccine’s trial results, while Pfizer’s stock was trading about 0.5% lower.
- Pfizer plans to submit the vaccine to U.S. regulators, aiming to provide a needed option against Lyme disease, which affects 476,000 Americans each year
An experimental Lyme disease vaccine from Pfizer PFE -0.74%decrease; red down pointing triangle and Valneva VLA -39.01%decrease; red down pointing triangle didn’t conclusively succeed in a large study, raising questions about the shot’s prospects.
While the shot was more than 70% effective at preventing the tick-borne disease in the trial, not enough people contracted the disease for the findings to be conclusive. Pfizer is pushing ahead with its plans to seek regulatory approval anyway, saying the study hit a different statistical measure and the shot showed “meaningful efficacy.”
Valneva’s stock fell 39% on the uncertainty. This vaccine is key for the French company, which has a chikungunya shot that ran into trouble with U.S. regulators last year over safety concerns. Pfizer, a far bigger company that is less reliant on the shot, was down about 0.5% in afternoon trading.
The vaccine, if approved, would provide a much-needed addition to the arsenal against Lyme disease. The tick-borne disease has been spreading across the U.S., but there have been few good medical options beyond antibiotics. A vaccine was pulled two decades ago after questions about its safety hurt demand.
No safety concerns were identified in Pfizer and Valneva’s 9,400-person trial. Annaliesa Anderson, Pfizer’s chief vaccines officer, called the study’s results “highly encouraging” and said it “creates confidence in the vaccine’s potential to protect against this disease that can be debilitating.”
Lyme disease is a bacterial infection that can be spread to humans by infected ticks, and affects an estimated 476,000 Americans each year. There currently aren’t any vaccines for people, though there is a shot for dogs.
Early Lyme symptoms include a rash, fatigue, muscle and joint pain, headache and fever, but it can often be overlooked or misinterpreted. Lyme disease is most common in the Northeast, Mid-Atlantic and upper Midwest regions of the U.S., and in recent years the disease has been spreading to other parts of the country.
Pfizer and Valneva studied their shot, which is administered in four doses over more than a year, in adults and children ages 5 and older.
An older Lyme disease vaccine, Lymerix, from a predecessor company to GSK, was on the market from 1998 until it was withdrawn in 2002. The company voluntarily withdrew it after lawsuits alleged it caused side effects such as arthritis. The lawsuits were settled in 2003.
GSK cited low demand for its withdrawal, rather than safety concerns. Many doctors and medical experts say there was never any definitive evidence that the old vaccine caused serious side effects such as arthritis or neurological problems.
Even so, some Lyme-disease patient advocacy groups that came out against the old vaccine have expressed concerns that the Pfizer-Valneva vaccine could carry risks similar to those alleged for Lymerix.
The Pfizer-Valneva vaccine is different from Lymerix in that it protects against six strains of the disease, whereas Lymerix protected against only one.
Valneva initially developed the new vaccine and Pfizer struck an agreement with the French drugmaker in 2020 to co-develop it. Pfizer will exclusively manufacture and market the shot, if it gets regulatory approval.
Analysts expect the shot, if approved, to begin generating revenue in 2028 and deliver sales of about $470 million in 2029, according to FactSet.