Merck puts 1,000-plus Zostavax lawsuits to bed after plaintiffs file for dismissal

After a drawn-out litigation process, Merck & Co. seems to have finally washed its hands of more than a thousand lawsuits tied to its shingles vaccine Zostavax.

Late last week, the U.S. Court of Appeals for the Third Circuit tossed an appeal to resurrect certain lawsuits claiming Merck’s popular shot caused patients to develop shingles.

The appeals court made its decision after the plaintiffs filed a voluntary dismissal some two years after logging a loss in Pennsylvania, court documents show.

With the appeals court snub, the plaintiffs could conceivably still take their cases to the Supreme Court.

Merck still faces claims from plaintiffs in other states who argue Zostavax caused “various other injuries” besides shingles plus those contending the vaccine causes hearing loss. As of summer 2021, Merck was facing some 1,950 lawsuits related to Zostavax. The December 2022 ruling against the plaintiffs knocked out 1,189 cases.

At the time, the court determined that the medical expert on deck to prove that Zostavax caused patients shingles failed to consider whether the plaintiffs’ disease occurred naturally because they’d had chickenpox as kids.

Chickenpox and shingles, also known as herpes zoster, are caused by the varicella-zoster virus. The judge overseeing the December 2022 dismissal pointed out that “[v]irtually all persons over the age of 30 in the United States have had chickenpox and carry the so-called wild-type virus in their systems.”

He added that Merck provided the court “uncontradicted medical authority” that a laboratory test of a person’s shingles rash was “the only way to tell whether the shingles was caused by the virus strain contained in Zostavax or by the wild-virus strain from chickenpox closeted in a person’s body.”

Merck, for its part, hasn’t sold Zostavax in the U.S. since 2020. The shot was once the premier shingles immunization in the states, but it was quickly usurped once GSK’s Shingrix hit the scene in 2017.

Earlier in 2022, meanwhile, Merck prevailed in another Zostavax case in Ohio when a federal judge tossed a lawsuit alleging the company misled consumers about the vaccine’s effectiveness, especially in older adults.