L. 109–148 (text) (PDF)), is a controversial tort liability shield intended to protect pharmaceutical manufacturers from financial risk in the event of a declared public health emergency.

The act specifically affords to drug makers immunity from actions related to the manufacture, testing, development, distribution, administration and use of medical countermeasures against chemical, biological, radiological and nuclear agents of terrorism, epidemics, and pandemics.

During and in the aftermath of the 2020–21 COVID-19 pandemic in the United States, PREPA is being invoked in a variety of lawsuits, many involving skilled nursing or assisted living facilities where COVID-19 countermeasures including the administration or non-administration of vaccines is said to have resulted in or contributed to resident deaths.

However, the primary effects of the legislation hinge on liability protections for drug companies, under provisions intended to remove financial risk barriers for any new vaccines that need to be rushed to market in case of an emergency.

Under PREPA, the HHS secretary will have primary responsibility for making decisions on whether or not to declare an emergency that would justify removing financial risk barriers, which otherwise would cause a prudent manufacturer to exercise caution.

Pursuant to such an emergency declaration, liability protection would extend to doctors and other individuals and organizations involved with countermeasures, which may include any medical product to prevent, treat, mitigate, or diagnose an epidemic.

[5] PREPA removes the right to a jury trial for persons injured by a covered vaccine, unless a plaintiff can provide clear evidence of willful misconduct that resulted in death or serious physical injury.

[6] Kennedy said the bill makes it "essentially impossible" for injured parties to sue for damages, and that the measure allows common diseases to be used as a reason to activate the liability shield.

[citation needed] When the PREPA legislation was presented, its broad liability shields, its potential for undermining state vaccine laws, and its consolidation of responsibility within the executive branch were misrepresented in Congress and media, according to critics, who note that it was portrayed instead as primarily concerned with preparations to combat the avian flu.