# PREP Act

> US federal law (2005) granting liability immunity for the development and deployment of medical countermeasures during a declared public health emergency.

Canonical source: https://hantatracker.fr/en/glossary/prep-act/

**Aliases**: Public Readiness and Emergency Preparedness Act, PREP Act declaration

The **PREP Act** (*Public Readiness and Emergency Preparedness Act*) is a US federal law from 2005 that allows the **Health Secretary (HHS)** to issue **targeted declarations** granting liability immunity to manufacturers, distributors and healthcare professionals for deploying **medical countermeasures** during a public health emergency. The goal: lift legal obstacles that would slow a rapid response to an epidemic threat.

## The mechanism

A PREP Act declaration is **not** a licence to ignore safety — it does not cover wilful misconduct or gross negligence. It simply recognises that, **within a declared public health emergency**, actors developing and administering countermeasures (drugs, devices, sometimes vaccines) must be able to act quickly without fear of being sued for foreseeable adverse effects. It has been activated for COVID-19, monkeypox and several other emergencies since 2005.

## The Andes virus declaration of 24 May 2026

On **24 May 2026**, HHS Secretary **Robert F. Kennedy Jr.** signed and had published in the Federal Register (document **2026-10539**) a **targeted declaration** on the Andes virus. Three points to remember:

- **Scope**: the [MV Hondius](/en/glossary/mv-hondius/) outbreak and its chain of transmission, not the Andes virus in general.
- **Covered countermeasure**: the **investigational use of favipiravir**, an RNA antiviral originally developed against influenza, as a potential treatment for hantavirus pulmonary syndrome.
- **Duration**: in force **until 18 July 2026**.

The declaration **does not cover a vaccine** and **does not prejudge** favipiravir's actual efficacy against the Andes virus — it only opens the way to framed compassionate use.

## A measured read

The declaration was publicly announced by RFK Jr. on his official @SecKennedy account the same day. For the bigger picture alongside the [GPMB](/en/glossary/gpmb/) diagnosis on global preparedness, see our breakdown [MV Hondius, a pandemic dress rehearsal](/en/articles/mv-hondius-pandemic-rehearsal-gpmb-2026-report/).