A PYMNTS Company

US Supreme Court Rejects Appeal in Merck Mumps Vaccine Antitrust Case

By  |  October 20, 2025

The U.S. Supreme Court has declined to hear an appeal from a group of physicians and healthcare providers who sought to revive an antitrust lawsuit against pharmaceutical company Merck & Co., according to Reuters. The decision effectively ends a decade-long legal battle that accused the drugmaker of misleading regulators to maintain its dominance in the mumps vaccine market.

    Get the Full Story

    Complete the form to unlock this article and enjoy unlimited free access to all PYMNTS content — no additional logins required.

    yesSubscribe to our daily newsletter, PYMNTS Today.

    By completing this form, you agree to receive marketing communications from PYMNTS and to the sharing of your information with our sponsor, if applicable, in accordance with our Privacy Policy and Terms and Conditions.

    The justices refused to review a lower court ruling that dismissed the case, which had concluded that Merck’s actions were shielded under a legal doctrine protecting companies from antitrust liability when their conduct involves influencing government decision-making. The lawsuit, first filed in 2012 by family doctors and physician organizations in New Jersey and New York, had sought monetary damages, per Reuters.

    At the core of the lawsuit were allegations that Merck provided false or misleading information to the U.S. Food and Drug Administration (FDA) to prevent competitors, including GlaxoSmithKline, from introducing a rival mumps vaccine. The plaintiffs argued that these alleged misrepresentations prolonged Merck’s monopoly on the mumps vaccine market for over a decade, leading to inflated prices and limited competition. According to Reuters, Merck was the sole manufacturer of a mumps vaccine in the United States from 1967 until 2022, selling it as part of the MMR-II vaccine, which also protects against measles and rubella.

    Related: Merck Bets Big on Respiratory Drug in $10 Billion Verona Pharma Deal

    The lawsuit also referenced concerns raised by the FDA in the 1990s regarding the vaccine’s potency near the end of its 24-month shelf life. Plaintiffs accused Merck of misleading the agency in later years about the vaccine’s effectiveness, asserting that the company artificially boosted its initial potency to sustain regulatory approval without altering its claims of efficacy.

    In response, Merck stated on Monday that the case “lacked any legal or factual basis,” and expressed satisfaction that the Supreme Court upheld previous court decisions dismissing the matter. The company emphasized that the ruling definitively closes the case in its favor, according to Reuters.

    Source: Reuters