Antiviral GHP-88310 blocks contact-mediated and airborne transmission in a ferret model of measles-like disease

The 2025/2026 measles resurgence in North America highlighted that antivirals may be valuable in protecting child health because of mounting vaccination hesitancy. The drug candidate GHP-88310 is an orally efficacious broad-spectrum orthoparamyxovirus polymerase inhibitor, but its effect on viral transmission is unclear. Here we used canine distemper virus, which causes measles-like disease in ferrets, and established direct-contact and airborne canine distemper virus transmission models to examine pharmacological suppression of virus spread. Prophylactic GHP-88310 administration alleviated clinical signs of direct contacts and all sentinels survived. Pre- and post-exposure prophylactic GHP-88310 given twice daily to air contacts prevented transmission. Once-daily prophylactic administration mediated complete survival with all air contacts undergoing seroconversion. Therapeutic treatment of air contacts mitigated clinical signs, and animals survived, whereas all vehicle-treated air contacts succumbed. Therapeutic treatment of infected source animals shortened the contagious phase by 5 days. These results establish conceptual proof that GHP-88310 can suppress social contact transmission. Therapeutic treatment of sources promises epidemiological gain in addition to therapeutic benefit.