A product liability lawsuit filed by a Utah woman claims that side effects of the shingles vaccine Zostavac caused her to suffer a stroke and left her with permanent vision loss, among other complications.

Roma Maurine Veater filed the complaint (PDF) earlier this month in the U.S. District Court for the Eastern District of Pennsylvania, indicating that Merck used an under-attenuated version of the live virus in the Zostavax vaccine, which can cause reactivation of thee herpes zoster virus, resulting in more persistent and severe shingles outbreaks, instead of creating an immunity to the virus.

Veater received a Zostavax inoculation in September 2017, for the prevention of shingles. However, shortly after receiving the shingles vaccine, she suffered an abrupt onset of vertigo, as well as vision loss and nausea. She was hospitalized and diagnosed with acute ischemic stroke, which she blames on the shingles vaccine side effects.

Zostavax was the first shingles vaccine approved in the U.S., and was widely used among older adults after it was introduced in 2006. The vaccine involves a single-dose injection, which contains a live virus designed to vaccinate older adults against the development of the disease. However, Zostavax has largely replaced by the medical community after a newer version of the shingles vaccine was introduced, as Zostavax was linked to a large number of reports involving severe complications, where individuals experienced more persistent shingles outbreaks, as well as other infections and auto-immune disorders, shortly after exposure to Zostavax.

“A risk of using a live virus vaccine is that it is not weakened enough or ‘under attenuated’,” the lawsuit notes. “Under-attenuated live virus creates an increased risk of developing the disease the vaccine was to prevent.”

The complaint joins hundreds of other Zostavax lawsuits filed by individuals throughout the U.S. Court System, each raising similar allegations that the Merck shingles vaccine contained a live-virus which was not sufficiently weakened to avoid reactivating the dormant virus in some individuals.

Given similar questions of fact and law raised in shingles vaccine lawsuits filed throughout the federal court system, the litigation has been centralized before U.S. District Judge Harvey Bartle III in the Eastern District of Pennsylvania, for coordinated discovery and pretrial proceedings.

As part of the coordinated litigation, Judge Bartle has scheduled a series of early “bellwether” trials, which are designed to help gauge how juries may respond to certain evidence and testimony that may be repeated throughout the claims. However, if Merck fails to reach Zostavax settlements or another resolution for the litigation, each individual lawsuit may eventually be remanded back to different U.S. District courts nationwide for separate trial dates in the future.