WHO adds ArkBio ́s RSV drug to its priority list

The World Health Organization added ArkBio’s antiviral drug Ziresovir to its PADO RSV Drug Development Priority List, recognizing it as a promising treatment for respiratory syncytial virus in children.

Why it matters: RSV is a major global cause of infant hospitalization. WHO’s prioritization via PADO could fast-track development and global adoption of effective pediatric RSV therapies, especially in low-resource regions.

Backstory: Ziresovir, developed by Shanghai-based ArkBio, is an orally administered RSV fusion (F protein) inhibitor. It binds to the pre-F protein conformation of the virus and prevents viral entry into human cells and has shown promising safety and efficacy results in early trials across Asia.

Big picture: RSV kills approximately 100,000 children under 5 and causes 3.6 million hospitalizations per year. With limited RSV treatments for young children, WHO’s backing positions Ziresovir to fill a critical therapeutic gap and support global pediatric health equity.

What is PADO?: PADO stands for Paediatric Drug Optimization. It is a WHO's legally binding international priority (based on WHA69.20 resolution) that accelerates the development of high-demand pediatric drugs by building consensus among regulators, funders, and manufacturers.