Pfizer’s Lyme disease vaccine trial failed, and the company is seeking FDA approval

Pfizer It said Monday it would seek regulatory approval for a Lyme disease vaccine candidate despite the vaccine’s failure in late-stage trials.

Pfizer said the vaccine missed the trial’s statistical target because there were not enough people in the study who had Lyme disease to be confident in the results. However, the company said the vaccine reduced the infection rate by more than 70% in people who received the vaccine compared to a placebo, an effectiveness that the company believes is strong enough to take to regulators.

“The efficacy demonstrated in the VALOR study of more than 70% is very encouraging and creates confidence in the vaccine’s ability to protect against this potentially debilitating disease,” Annalisa Anderson, Pfizer’s chief vaccine officer, said in a statement.

The Lyme disease vaccine is not expected to become Pfizer’s top seller, with company partner Valneva estimating peak annual sales at $1 billion. Pfizer expects its total revenue to reach about $60 billion this year, and its Covid-19 vaccine represents more than $5 billion of that forecast.

But Pfizer described the Lyme vaccine results as one of its main catalysts this year, and represented an opportunity 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 called for tougher scrutiny of vaccines could be risky for Pfizer, and could serve as a litmus test for vaccine policy in the United States.

Lyme disease is a disease caused by bacteria that is usually 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 each year, according to estimates from the Centers for Disease Control and Prevention.

Although the disease is widespread, especially in the Northeast, there is no vaccine available for humans. The company it would later become GlaxoSmithKline In 1998, Limerex introduced an injection called Limerex, but withdrew it only a few years later after public concerns about safety dampened demand. This experience has hampered the development of Lyme vaccines for humans, although several companies now make them for dogs.

Pfizer and Valneva have had their own setbacks. In 2023, companies dropped about half of their Phase 3 trial participants due to quality concerns with third-party clinical trial site operator Care Access. The experiment initially registered about 18,000 people, and after the cuts, it ended with about 9,400 people.

The companies’ vaccine targets the outer surface protein A of the bacteria that causes Lyme disease. The vaccinated person creates antibodies that are transmitted to the tick and prevent the bacteria from being transmitted from tick to human. The series includes three doses in the first year, then a booster dose the following year.

The companies said they did not notice any safety concerns in the trial.