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Pfizer on Monday said it will seek regulatory approval for a Lyme disease vaccine candidate despite the shot failing a late-stage trial.
Pfizer said the vaccine missed the trial’s statistical goal because not enough people in the study contracted Lyme disease to be confident in the results. Still, the company said the shot reduced the rate of infection by more than 70% in people who received the vaccine versus placebo, efficacy the company thinks is strong enough to take to regulators.
“The efficacy shown in the VALOR study of more than 70% is highly encouraging and creates confidence in the vaccine’s potential to protect against this disease that can be debilitating,” Pfizer Chief Vaccines Officer Annaliesa Anderson said in a statement.
A vaccine for Lyme disease isn’t expected to become a best-seller for Pfizer, with the company’s partner Valneva estimating peak annual sales of $1 billion. Pfizer expects overall revenue of around $60 billion this year, with its Covid-19 vaccine representing more than $5 billion of that forecast.
But Pfizer had billed the Lyme vaccine results as one of its major catalysts this year, and it represented a chance to introduce the only human vaccine for Lyme disease.
Moving forward with a shot that technically failed a clinical trial under an administration that has preached stricter scrutiny for vaccines may prove risky for Pfizer, and it could serve as a litmus test for vaccine policy in the U.S.
Lyme disease is an illness caused by bacteria most commonly spread to humans from ticks. It can cause arthritis, muscle weakness and pain. About half a million Americans are diagnosed with or treated for Lyme disease every year, according to estimates from the Centers for Disease Control and Prevention.
Despite the disease’s prevalence, especially in the Northeast, there isn’t a vaccine for humans available. A company that would later become GSK introduced a shot called LYMErix in 1998 but pulled it only a few years later after public concerns about safety tanked demand. That experience hobbled development of Lyme vaccines for humans, though multiple companies now make them for dogs.
Pfizer and Valneva have faced their own setbacks. In 2023, the companies dropped about half of the participants in the Phase 3 trial because of quality concerns with third-party clinical trial site operator Care Access. The trial had initially enrolled about 18,000 people and after the cuts ended up with about 9,400.
The companies’ vaccine targets the outer surface protein A of the bacteria that cause Lyme disease. A vaccinated person creates antibodies that are passed to a tick and prevent the bacterium from being transferred from the tick to the human. The series involves three shots in the first year, then a booster dose the following year.
The companies said they didn’t observe any safety concerns in the trial.
