The US Food and Drug Administration (FDA) recently revisited the topic of drugs for liver infection through a newly issued guidance document on hepatitis D virus (HDV) in October 2019. Deborah Komlos at Clarivate Analytics illustrates how the guidance document, titled ‘Chronic Hepatitis D Virus Infection: Developing Drugs for Treatment’, provides recommendations regarding clinical trial designs for the development of drugs and biologics to support an indication for the treatment of chronic HDV infection.