A scientific trial using the experimental drug remdesivir to treat COVID-19 in monkeys has been successful, according to a preliminary report.
Scientists infected two groups of six rhesus macaque monkeys with the coronavirus and treated half with remdesivir intravenously.
None of the animals given the drug showed "signs of respiratory disease" after treatment, and scans showed their lungs contained less substances linked to pneumonia, the report states.
How the study will translate to treating infected humans is still unknown, researchers say.
The monkeys were dosed 12 hours after they were infected and once a day for six days after, which follows the same schedule as humans in similar trials.
Researchers checked the monkeys’ symptoms and monitored how much of the virus they were carrying. They were autopsied after seven days.
The results indicated that as early as 12 hours after the first treatment was administered, levels of the virus declined in the monkeys’ lower respiratory system, the team said.
Early administration of the drug could be a key in the trial’s success, researchers said. That’s because this type of antiviral becomes less effective against acute viral respiratory tract infections when the start of treatment is delayed.
To receive the maximum results, “remdesivir treatment in COVID-19 patients should be initiated as early as possible,” the study states.
“Therapeutic remdesivir treatment initiated early during infection has a clear clinical benefit in SARS-CoV-2-infected rhesus macaques,” the report states. “These data support early remdesivir treatment initiation in COVID-19 patients to prevent progression to severe pneumonia."
The study, which is awaiting peer review, cautions it is unknown how the results will translate to humans.
"Due to the acute nature of the disease in rhesus macaques, it is hard to directly translate the timing of treatment used to corresponding disease stages in humans,” it states.
Rhesus macaque monkeys are often used in clinical trials because they share DNA with humans, according to the National Institutes of Health.
They have been used to help find treatments for Zika virus, HIV and other diseases.
Andrew Preston, a reader in microbial pathogenesis at the University of Bath, told Newsweek the monkeys received treatment "very soon" after they were infected. He said by the time symptoms of the virus appear in humans, it is often later than the 12-hour mark where the monkeys were treated.
Scientists at the National Institute of Allergy and Infectious Diseases, National Institutes of Health, and remdesivir creator Gilead Sciences worked on the study.
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