Dressen v. AstraZeneca Pharmaceuticals LP, 2026 WL 2122898(10th Cir. July 23, 2026), extends to four weeks our streak of discussing favorable vaccine decisions – this time involving product liability.

In a well written, fully reasoned, reported decision, the Tenth Circuit reversed the worst Public Readiness and Emergency Preparedness (PREP) Act preemption decision to arise from the COVID pandemic.  We clobbered the trial court decision (the only one in the country to allow any liability theory against an actual vaccine manufacturer) here.  

The plaintiff in Dressen participated as a test subject in a Covid-19 vaccine clinical trial, signing an informed consent form (ICF), which among other things, disclosed federal limits on suits over the then-experimental vaccine. Alleging injury from the vaccine, the plaintiff sued, claiming a contract right to recover for the claimed injuries. She pointed to language in the ICF that she asserted amounted to a promise by the defendant to cover the costs of any medical care needed to treat injuries from the vaccine. 

The trial court held that PREP Act preemption did not extend to contract claims. It reasoned (if that’s what you want to call it) that the “administration” or “use” of a covered countermeasure cannot, by itself, cause a breach of contract, and the statute requires that a claim for loss be causally related to a covered countermeasure. 

The Tenth Circuit reversed, but before it could do so, it needed to ascertain whether the matter was appealable under the collateral-order doctrine. The three requirements of that doctrine are that the issue below had to have been conclusively determined below, that the issue to be resolved was important, and that it would be effectively unreviewable on appeal from a final judgment. The first two criteria were easily satisfied. More tricky was the third issue. If the defendant merely relied on its interest in avoiding trial to show an injury that could not be fixed on appeal from a final judgment, that would fall short. (What defendant would not prefer to avoid a trial?) But the PREP Act contained a form of congressionally created statutory immunity. That was a game changer:  “Once Congress has declared that an interest in avoiding trial is of sufficient importance to create an immunity from suit, we must defer to that assessment.” Accordingly, the Tenth Circuit had jurisdiction to consider, and reverse, the execrable decision below. 

Under the ICF, the plaintiff’s ability to sue over vaccine-related injuries was expressly subject to the in-force PREP Act declarations. Covid vaccines were the subject of such a declaration. The PREP statute provides immunity to the provision of covered countermeasures by covered persons.  The vaccine and its manufacturer obviously qualified. Further, the immunity expressly applied to clinical investigations and extended to all claims of “any type of loss,” not just tort claims.  “Any” means any. Given the statutory language, the Tenth Circuit saw “irony, if not chutzpah,” in the plaintiff’s attempt to create an extra-statutory contract exception that would allow recovery of the same damages. If Congress intended to exclude contract claims, it would have done so expressly.  

The plaintiff invoked various canons of statutory construction in an effort to read contract claims out of the PREP Act. In particular, the plaintiff relied upon ejusdem generis, negative implication, noscitur sociis, and the presumption against surplusage.  With a little help from Scalia/Garner’s excellent book, Reading Law: The Interpretation of Legal Texts, the Tenth Circuit swatted away the plaintiff’s effort to deploy those canons to rewrite the PREP Act. It is an impressive performance by the Tenth Circuit and, momentarily, reminded us of why we took Latin in high school. 

The court did not buy the plaintiff’s suggestion that PREP Act immunity could not reach claims, such as her contract claim, that did not explicitly reside on the vaccine compensation table. Further, given the expressed intent of Congress in the PREP Act, it was not “absurd” (as the plaintiff contended) to preclude contract claims arising from investigational countermeasures.  

In a footnote, the Tenth Circuit rejected the plaintiff’s argument that there should be a presumption against PREP Act preemption of state law claims because — and forgive us for the use of all caps, but there are enough recalcitrant courts out there such that hollering is warranted — THERE IS NO PRESUMPTION AGAINST EXPRESS PREEMPTION. SCOTUS has said so explicitly and clearly at least once, and the rest of its recent commentary on the issue has been death by silence.  Almost all appellate courts have renounced the presumption (except, sigh, our hometown Third Circuit).  And the silliness of the presumption has been decreed by the highest of all authorities — this blog. Please stop it with the out of date, unlawful presumption against express preemption. 

The plaintiff also urged the Tenth Circuit to apply the doctrine of constitutional avoidance. What constitutional issue needed avoiding? According to the plaintiff, PREP Act would be an uncompensated taking of contract rights in violation of the Fifth Amendment. The Tenth Circuit rejected that argument. “Statutory limits on liability are a commonplace,” and are not takings, so there is no legitimate constitutional issue to avoid.  Moreover, such avoidance makes no sense in the face of a clearly written statute that offers no special favor for contract claims.  

The plaintiff also argued that immunity should not apply because her injuries were not caused by the investigational vaccine but, rather, were caused by the defendant’s failure to live up to its promise. As we have already seen, that argument worked below.  It is undeniably clever, but also undeniably wrong. Applying the concept of but-for causation, the Tenth Circuit held that there can be multiple causes. Call the plaintiff’s injury the result of a breach if you want, but it was also allegedly the result of the vaccine. “Here, the vaccination was a necessary condition; it was therefore a but-for cause.” Hello PREP Act immunity, goodbye semantics. 

The only bone the Tenth Circuit tossed the plaintiff’s way was on the issue of whether the terms of the ICF might have equaled a waiver of PREP Act immunity. The trial court had not gotten to that issue, and the Tenth Circuit would not either: “We leave to the district court on remand to determine in the first instance whether PREP Act immunity can be waived and, if so, whether it was waived in this case.”

If you find vaccine litigation interesting, as we apparently do, you might want to refer to our PREP Act preemption scorecard and our posts, here and here, on the COVID PREP Act declarations.