Antiviral

• The FDA has approved ensitrelvir, an oral antiviral medication specifically designed to prevent COVID-19 after a person has been exposed to the virus. • Approval follows the phase III SCORPIO-PEP trial, which demonstrated that the drug reduced the risk of developing COVID-19 by more than half for individuals who were household contacts of an infected person. • This marks a significant shift in prevention strategy, though the medication is currently not approved for treating active COVID-19 infections within the U.S.

• Shionogi has received FDA approval for its protease inhibitor, ensitrelvir, specifically for use in the prevention of COVID-19. • This regulatory win follows a previous failure by the company to demonstrate the drug's effectiveness as a primary treatment for U.S. patients. • The approval is significant as it expands the available preventative options against the virus, leveraging a drug already approved in Japan.

• Researchers tested ARN-75039, an orally bioavailable small-molecule inhibitor, as a potential therapeutic against Lassa virus, which causes Lassa fever—a disease for which no preventative vaccine currently exists. • The compound represents a new approach to treating Lassa virus infection through direct viral entry inhibition rather than vaccines. • This research advances therapeutic options for a high-consequence pathogen that poses public health concerns, particularly in West African endemic regions.