Merck escapes nearly 1,200 Zostavax shingles vaccine lawsuits as plaintiffs' testimony falls short

Following a court judgment in its favor last year, Merck & Co. is formally bidding adieu to more than 1,000 lawsuits alleging its shingles vaccine Zostavax caused patients to develop the disease.

Tuesday, a Pennsylvania federal judge threw out exactly 1,189 cases against Merck in the four-year-long group of cases.

The plaintiffs in the now-dismissed clutch of lawsuits argued Zostavax caused their shingles. But the medical expert attempting to back up that claim failed to consider whether the plaintiffs’ disease occurred naturally because they’d had chickenpox as kids, according to court filings published this week.

Plaintiffs in the sprawling legal action were divided into three groups. Merck still has to face claims from those who argue Zostavax caused “various other injuries” besides shingles plus plaintiffs contending the shot causes hearing loss.

Chickenpox and shingles, also known as herpes zoster, are caused by the varicella-zoster virus. The judge overseeing the 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.”

Merck furnished the court with “uncontradicted medical authority” that a laboratory test of a person’s shingles rash is “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,” Pennsylvania federal Judge Harvey Bartle III wrote in an order this week.

“Plaintiffs concede that it cannot be determined which strain of the virus caused shingles simply by how the rash appears,” the judge added.

In March, the court granted Merck’s motion for what’s known as a Lone Pine order, which demanded that all plaintiffs in the now-dismissed clutch of cases present lab reports or other records clearly identifying that their disease was caused “vaccine-strain varicella zoster virus.”

But "not one" of the plaintiffs "provided the required laboratory report or laboratory equivalent documentation,” the judge wrote this week.

In turn, the court granted Merck’s motion to dismiss.

As of last summer, Merck still faced some 1,950 lawsuits related to Zostavax. This week’s ruling shelves a significant chunk of those.

Once the head honcho on the shingles scene, Merck’s Zostavax was quickly eclipsed by GSK’s Shingrix following that shot’s launch in 2017. Merck hasn’t sold Zostavax in the U.S. since 2020.

In the time since Zostavax’s stateside discontinuation, Merck has notched a number of wins in its litigation, including Bartle’s summary judgment of a bellwether case last July.

Earlier this year, Merck prevailed in another Zostavax case in which an Ohio federal judge scrapped a lawsuit alleging the company misled consumers about the vaccine’s effectiveness, particularly in older adults.

Merck's win isn't the only recent case where the facts presented by plaintiffs fell short. Pfizer, GSK, Sanofi and Boehringer Ingelheim this week eluded some 50,000 claims after U.S. District Judge Robin Rosenberg determined plaintiffs' experts had used "unreliable methodologies” to argue the fallen heartburn med Zantac causes cancer.