Zostavax Shingles Vaccine Effectiveness ‘Waned Substantially’ After 10 Years: Study

Findings come as Merck faces lawsuits over Zostavax, alleging the shingles vaccine was ineffective and that the drug maker failed to disclose serious risks associated with the injection.

New research suggests that protections provided by the Zostavax shingles vaccine appear to begin to wear off after about a decade, raising concerns about the long-term effectiveness of the injection, which has also been linked to a risk of severe and debilitating injuries for some users.

In findings published this month in the medical journal The BMJ, researchers from Kaiser Permanente and Merck & Co., Zostavax’s manufacturer, found that the shingles vaccine was only about 15% effective at preventing shingles after 10 years.

Merck introduced Zostavax in 2006, as the first vaccine approved in the United States for prevention of shingles, which involved a single-dose injection that contained a live virus that was intended to prevent development of the painful condition. However, several thousand Zostavax lawsuits have been filed by individuals who allege the vaccine is ineffective and may actually cause some users to experience persistent shingles outbreaks the injection was designed to prevent, as well as various neurological problems, autoimmune diseases, vision loss and hearing damage.

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Zostavax Lawsuits

Side effects of the shingles vaccine Zostavax may result in the development of a painful and persistent strain of shingles


In this latest study, researchers looked at data on more than 1.5 million people ages 50 or older, who were part of the Kaiser Permanente Northern California healthcare delivery system from 2007 through 2018. They looked for those who had received the vaccine and its effectiveness at preventing shingles, postherpetic neuralgia and herpes zoster ophthalmicus. They also looked at hospital admissions for shingles.

According to the findings, even at first injection, Zostavax was only 67% effective at preventing shingles. That effectiveness begins to drop off immediately, resulting in an only 15% effectiveness after a decade.

Similar large drops were seen in the vaccine’s protection against related illnesses. Effectiveness against postherpetic neuralgia dropped from 83% to 41%. Herpes zoster ophthalmicus prevention effectiveness dropped from 71% to 29between five and eight years after a Zostavax injection. Protection from admissions to hospitals for shingles went from 90% to 53%, with the drop occurring between five and eight years, the findings indicate.

“Vaccine effectiveness waned substantially yet some protection remained 10 years after vaccination,” the researchers concluded. “After 10 years, protection was low against herpes zoster but higher against postherpetic neuralgia.”

Zostavax Shingles Vaccine Lawsuits

The findings come as Merck continues to face product liability lawsuits alleging that the drug maker withheld critical information about the potential side effects of Zostavax from users and the medical community, while overstating the effectiveness of the vaccine.

Each of the lawsuits raises similar claims, indicating that the shingles vaccine caused users to develop severe versions of the condition the injection was designed to prevent. Given similar questions of fact and law raised in complaints filed throughout the federal court system, all Zostavax lawsuits have been centralized before U.S. District Judge Harry Bartle in the U.S. District Court for the Eastern District of Pennsylvania, as part of a federal multidistrict litigation (MDL).

In December 2022, Judge Bartle dismissed Zostavax vaccine lawsuits involving claims that the vaccine gave them shingles, which included about 1,200 claims. Other cases, which include injuries from autoimmune disorders, paralysis, strokes, hearing loss and other injuries have been allowed to move forward.

In May, plaintiffs’ whose cases were dismissed filed an appeal with the 3rd U.S. Circuit Court of Appeals, which heard oral arguments on the issue last month. A verdict is still pending.


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