A new drug candidate being developed at Georgia State University has shown promise in treating measles and croup, raising hopes for an effective antiviral treatment against these highly contagious respiratory infections. The compound, designated GHP-88310, is described by researchers as the most potent inhibitor of the orthoparamyxovirus family they have encountered in years of work.
GHP-88310 is a broad-spectrum non-nucleoside inhibitor that targets the viral polymerases — the machinery viruses use to copy their genetic material. By blocking this process, the drug prevents the virus from replicating inside host cells. Researchers say it also protects against the virus’s attempts to evade the immune system, a challenge that has hampered treatments for other diseases such as Covid-19.
The drug is taken orally once a day and has shown high tolerability in animal studies. In seven-day trials, daily doses of up to 2,000 mg per kilogram of body weight were well tolerated in rats, mice, ferrets and dogs. “High potency and excellent tolerability ensure a very wide safety margin, which is essential for a drug candidate developed for the treatment of highly vulnerable patient groups and children,” said Richard Plemper, director of the Center for Translational Antiviral Research at Georgia State.
Efficacy data from animal models reinforces its potential. In cotton rats infected with human parainfluenza virus type 3 (HPIV3), the drug significantly reduced viral load in the respiratory tract. In ferrets infected with canine distemper virus — a related morbillivirus — it led to complete survival. The compound also demonstrated sterilising activity against HPIV3 in human airway epithelium organoids, laboratory-grown models that mimic the respiratory tract.
Originally developed as a clinical candidate analogue known as EIDD-3608, GHP-88310 improved upon earlier compounds by combining enhanced oral efficacy with favourable tolerability in non-rodent species. The research, led by senior postdoctoral fellow Carolin Lieber, was initially published as a preprint on bioRxiv in December 2025 and later appeared in the journal Science Advances.
Limited treatment options and growing need
Currently, there are no federally approved antiviral drugs specifically for treating measles beyond symptom management, the researchers note. Croup, an infection of the upper airway that causes difficulty breathing, is typically treated with steroid medication for more severe cases, and mild cases are managed with supportive care. No specific antiviral drug is approved for croup.
Measles can be prevented with two doses of the measles-mumps-rubella (MMR) vaccine, but vaccine coverage has slipped. For the human parainfluenza viruses that cause croup, bronchitis and pneumonia in infants, there are no vaccines or therapies available. HPIV3 was the primary target when researchers began developing GHP-88310; measles was identified as a secondary use.
The need for effective treatments has become more urgent as vaccination rates fall. The United States declared measles eliminated in 2000, but a resurgence driven by declining immunisation has seen nearly 2,000 measles cases this year, most of them in people under 19. Around 3 per cent of US children get croup annually. In the UK, the situation is similarly serious: the country lost its measles elimination status in January 2026 after a sharp rise in cases. In 2024, England recorded 2,911 laboratory-confirmed measles cases, the highest since 2012, and in 2025 a child died from the disease.
“To prevent measles from spreading, about 95 per cent of the population needs to be vaccinated with the MMR vaccine,” said Jennifer Nuzzo, director of the Pandemic Center at Brown University, in an October interview. “That level of coverage creates what’s called herd immunity.” She noted that the US has slipped below 90 per cent nationally, with some communities having much lower rates. In the UK, official figures show that only 84.4 per cent of children had received both MMR doses by their fifth birthday in 2024, well below the 95 per cent target. In some London boroughs, coverage is as low as 58.3 per cent for two doses in five-year-olds.
The Georgia State research programme was specifically designed to address the needs of children and immunocompromised patients, who account for the majority of croup and measles cases. “Re-emerging orthoparamyxoviruses such as the parainfluenza viruses and measles virus are a major threat to children and vulnerable groups such as the immunocompromised,” said Plemper. The drug’s wide safety margin and oral administration make it particularly suitable for these populations. Despite the progress, developing antivirals for measles has historically been challenging, with many compounds showing efficacy only when given very early after exposure. GHP-88310 represents a significant step forward in overcoming these hurdles, researchers say.