Lawsuits claiming Merck lied about mumps vaccine efficacy headed to trial

U.S. District Judge C. Darnell Jones II

Two lawsuits claiming Merck ($MRK) lied about the efficacy of its mumps vaccine won't be going away anytime soon. A federal judge in Pennsylvania refused to dismiss the suits, filed by a pair of whistleblowers and a group of doctors and payers, and now, they're on their way to trial.

On Thursday, U.S. District Judge C. Darnell Jones II ruled that the whistleblowers--two former Merck virologists--had sufficiently showed that the company may have misstated the vaccine's efficacy to the government, Law360 reports. And the direct purchasers produced enough evidence to establish that those false statements could have helped give Merck a monopoly, the judge said. Now, the plaintiffs will have to prove their cases at trial.

Merck has been the sole manufacturer with an FDA license to produce mumps vaccine since 1967, the news service points out, and the company has long touted a 95% efficacy rate for the shot. The drugmaker brought in $621 million on mumps vaccine sales last year, between its M-M-R II vaccine and ProQuad, a pediatric combo jab. 

But rather than using the "gold standard" approach and testing the vaccine against a wild-type mumps virus, Merck tested it against the attenuated virus strain that had created the vaccine in the 1960s--likely overstating the vaccine's effectiveness, the whistleblowers claim, according to the judge's memorandum. And if Merck "fraudulently misled the government and omitted, concealed, and adulterated material information regarding the efficacy of its mumps vaccine" in violation of the False Claims Act, as they allege, it may have discouraged competition. 

"As with the market for any product, a potential competitor's decision to enter a market hinges on whether its product can compete with those products already being sold in the market," the complaint reads, as quoted by Law360. "If an existing vaccine is represented as safe and at least 95% effective, as Merck has falsely represented its vaccine to be, it would be economically irrational for a potential competitor to bring a new mumps vaccine to the relevant market," the suit claims.

The way Merck sees it, whether it misstated the vaccine's efficacy is a matter for the FDA to investigate. The company argued that the whistleblowers' claims "rest on a finding that the vaccine label is misbranded, a determination which should fall squarely under the 'scientific expertise' and 'regulatory discretion'" of the agency, the memorandum says.

But Jones didn't agree, and now it'll be up to the courts to decide--a prospect that pleases Constantine Cannon, which is representing the whistleblowers, and Robins Kaplan Miller & Ciresi, representing the direct purchasers. "This decision brings us one step closer to shining a light on Merck's deceptive business practices so that new and more effective vaccines will ultimately be developed in the future," Robins Kaplan Miller & Ciresi lawyer Kellie Lerner said in a statement.

- get more from Law360 (reg. req.)
- read the judge's memorandum (PDF)

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