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We’ve discussed our Drug and Device Law Blog elder care duties before and how it has educated us about health issues faced by the senior population.  Shingles is one health risk that increases as you get older.  It is often described as a painful rash, but “painful rash” doesn’t really capture how bad shingles can be.  “Intense burning sensation” with pain that “can last for months or even years after the rash goes away” is closer, but still falls short of the acute reality of the experience.

Shingles is caused by the varicella-zoster virus, the same virus that causes chickenpox. If you’ve had chickenpox, you have the varicella-zoster virus in your body and, if it reactivates as you age, it will manifest as shingles.  Fortunately, vaccines can provide protection. 

But where there are vaccines, there will be litigation, and we’ve written before about litigation involving one of the shingles vaccines, Zostavax.  From a defense perspective, the In re Zostavax MDL has had its ups and downs, but mostly ups. 

On the downside, the MDL judge recently gave 43 plaintiffs a pass for failing to serve their complaints within 90 days as Federal Rule of Civil Procedure 4(m) requires.  See In re Zostavax (Zoster Vaccine Live) Prods. Liab. Litig., 2023 U.S. Dist. LEXIS 138412, 2023 WL 5044944 (E.D. Pa. Aug 8, 2023).

But on the upside, the MDL judge has not always indulged plaintiffs who fail to follow through on their procedural obligations.  He dismissed—with prejudice—the claims of a plaintiff who failed to timely serve discovery (the ever-problematic “plaintiff fact sheets” found only in MDLs).  See In re Zostavax (Zoster Vaccine Live) Products Liability Litigation, 2022 U.S. Dist. LEXIS 143883, 2022 WL 3309471 (E.D. Pa. Aug. 11, 2022).

In fact, Zostavax has made our year-end “best of” lists twice, in 2022 (#10) and 2021 (honorable mention).  The Court entered a Lone Pine order with teeth in In re Zostavax (Zoster Vaccine Live) Products Liability Litigation, 2022 U.S. Dist. LEXIS 57935, 2022 WL 952179 (E.D. Pa. March 30, 2022), and In re Zostavax (Zoster Vaccine Live) Products Liability Litigation, 2022 U.S. Dist. LEXIS 219261, 2022 WL 17477553 (E.D. Pa. Dec. 6, 2022), requiring all plaintiffs alleging one type of injury (vaccine-induced shingles) to disclose the results of a genetic test distinguishing between wild varicella virus and the weakened, vaccine strain, and dismissing the claims of plaintiffs who lacked proof their shingles was from the vaccine strain. The MDL Court also entered summary judgment in 2021 against five bellwether plaintiffs after excluding all their experts on Rule 702 grounds.  See In re Zostavax (Zoster Vaccine Live) Products Liability Litigation, 579 F. Supp. 3d 675 (E.D. Pa. 2021).

Earlier this year, the MDL Court also dismissed some claims on “warning causation” grounds.  Certain California plaintiffs claimed there was a failure to warn about the risk of peripheral neuropathy, but the prescribing physician “never said that knowledge of such a risk would have changed her decision to prescribe it” and plaintiffs’ experts said they only cared about “common” side effects and offered no opinion about “the incidence of peripheral neuropathy as a side effect of Zostavax.”  In re Zostavax (Zoster Vaccine Live) Products Liability Litigation, 2023 U.S. Dist. LEXIS 45440, 2023 WL 2562981 (E.D. Pa. March 16, 2023).  In other words, these plaintiffs hadn’t shown that the alleged failure to provide the peripheral neuropathy warning would have mattered.

And that brings us to the latest Zostavax order, In re Zostavax (Zoster Vaccine Live) Products Liability Litigation, 2023 WL 6465837 (E.D. Pa. Oct. 4, 2023), and it’s another good one.  It involved a bellwether plaintiff who’s alleged Zostavax injury was “persistent daily headache” (or “PDH”), which she described as mild headaches lasting “fifteen to thirty seconds.”  Id. at *2.  

To support her case, this plaintiff offered the testimony of Dr. Joseph Jeret, apparently a frequent-flyer expert witness available to cover any number of medical specialties and alleged injuries.  Dr. Jeret opined that Zostavax can cause PDH (general causation) and in fact did cause PDH in this plaintiff (specific causation). 

But Dr. Jeret never met or examined the plaintiff, and developed his opinion based on a review of a select 44 pages of her medical records and two depositions.  Suffice to say the opinion already had a shaky foundation.

Next, Dr. Jeret’s general causation opinion (that Zostavax can cause PDH) was based on, in Daubert and General Electric Co. v. Joiner, 522 U.S. 136, 146 (1997), terms, ipse dixit.  His chain of not-really-connected links was as follows:

First, it is undisputed that Zostavax is a live-attenuated virus vaccine, which can cause infections and headaches. The Zostavax warning label confirms that headaches can result. Second, the most commonly known trigger of PDH is “infection and flu-like illness.” Id. Dr. Jeret notes that 22% of the cases of PDH are a result of infection. Third, the odds of contracting PDH from an infection increases in individuals with immunosenescence, that is, individuals whose immune systems have weakened with age, and in individuals with prior trauma. Fourth, Dr. Jeret concludes Zostavax can cause PDH in older people.

Id. at *3.

As the Zostavax judge quickly surmised, Dr. Jeret’s general causation conclusion was not reliable because:

It does not follow that simply because Zostavax can cause an infection and headaches in older people or people that have experienced head trauma, that it can cause PDH.

Id. at *4.  No epidemiology supported the conclusion that Zostavax causes PDH.  The Zostavax label reporting headaches as a common adverse event does not mean that Zostavax causes PDH, a distinct medical condition.  Notably, Dr. Jeret’s opinion that “any infection from Zostavax could result in PDH is merely a theory based on biological plausibility” and “is no more reliable than an opinion that moonlight can cause skin cancer merely because there is a study that sunlight can cause skin cancer.”  Id. 

Dr. Jeret’s specific causation opinion also fell short of the admissibility mark.  His PDH diagnosis did not fit the accepted diagnostic criteria, and he failed to account for the plaintiff’s pre-vaccination history of migraine headache in reaching his PDH diagnosis.  He basically decided Zostavax caused PDH in the plaintiff based on temporal proximity, and never performed a differential diagnosis. 

Because Dr. Jeret did not employ reliable methods in reaching his general or specific causation opinions, his testimony was excluded.  Assuming this plaintiff has no other expert testimony on medical causation, we can only assume that summary judgment will be forthcoming.

A few days after this post, the Zostavax court issued another Rule 702 opinion, In re Zostavax (Zoster Vaccine Live) Prods. Liab. Litig., 2023 U.S. Dist. LEXIS 183958, 2023 WL 6626581 (E.D. Pa. Oct. 11, 2023). This latest opinion relates to a claim that his Zostavax inoculation caused one plaintiff to develop Guillian-Barré syndrome. The experts in this case theorized that administration of a live-attenuated virus process can trigger an autoimmune response through a process called “molecular mimicry”. This time, the Zostavax court concluded that the general causation opinions were sufficiently substantiated (including through epidemiological evidence) to meet Rule 702’s admissibility standard. As to specific causation, however, the expert testimony still fell short. The specific causation opinion was based on a differential diagnosis, but one that did not consider whether the plaintiff’s Guillian-Barré syndrome was idiopathic–even though 1/3 to 1/2 of Guillian-Barré syndrome cases have an idiopathic cause. Failure to consider an obvious alternative cause, without good grounds for doing so, renders an expert’s differential diagnosis opinion unreliable, requiring its exclusion under Rule 702 (and Daubert).