Remdesivir may be a highly effective antiviral against SARS-CoV-2, the virus that causes Covid-19, according to a new single-patient study that contradicts previous research which found the drug had no impact on death rates from the disease.
The researchers from the University of Cambridge in the UK who gave the drug to a patient with Covid-19 and a rare immune disorder, observed a dramatic improvement in his symptoms and the disappearance of the virus.
Scientists had previously pinned hope on Remdesivir which was originally developed to treat Hepatitis C and subsequently tested against Ebola.
However, results from large clinical trials have been inconclusive, and the World Health Organization (WHO) announced in October that the drug did not significantly reduce mortality rates.
The new study, published in the journal Nature Communications, used a different approach to determine the effects of the drug on Covid-19 in a closely monitored patient.
"There have been different studies supporting or questioning Remdesivir's effectiveness, but some of those conducted during the first wave of infection may not be optimal for assessing its antiviral properties,” James Thaventhiran from the University of Cambridge said.
The researchers examined the case of a 31-year-old man with XLA, a rare genetic condition that affects the body's ability to produce antibodies and hence fight infection.
The patient's illness began with fever, cough, nausea and vomiting, and on day 19 he tested positive for SARS-CoV-2.
His symptoms persisted and on day 30 he was admitted to hospital, where he was given supplemental oxygen due to breathing difficulties.
The man's fever and inflammation of the lungs persisted for longer than 30 days, but without causing severe breathing problems or spreading to other organs.
The researchers said this may have been due to his inability to produce antibodies -- although antibodies fight infection, they can also cause damage to the body and even lead to severe disease.
At first, the patient was treated with hydroxychloroquine and azithromycin, which had little effect, and the treatments were stopped on day 34, they said.
The patient then commenced a ten-day course of Remdesivir.
The researchers found that within 36 hours, his fever and shortness of breath had improved and his nausea and vomiting ceased, adding that rising oxygen saturation allowed him to be taken off supplemental oxygen.
This dramatic clinical response was accompanied by a progressive decrease in levels of C-reactive protein (CRP), a substance produced by the liver in response to inflammation, according to the researchers.
Doctors also saw an increase in the number of his immune cells known as lymphocytes, and chest scans showed that his lung inflammation was clearing, they said.
The patient was discharged on day 43. A week after discharge, the patient's fever, shortness of breath and nausea returned.
The man was readmitted to hospital on day 54 and given supplemental oxygen.
He again tested positive for SARS-CoV-2, was found to have lung inflammation, and his CRP levels had increased and his lymphocyte count fallen.
On day 61, the patient began treatment with a further ten-day course of Remdesivir, according to the researchers.
The study found that, once again, his symptoms improved rapidly, his fever dropped and he was taken off supplemental oxygen. His CRP and lymphocyte count normalised.
Following additional treatment with convalescent plasma on days 69 and 70, he was discharged three days later and is no longer symptomatic.
The team found that the patient's virus levels fell progressively during his first course of Remdesivir, corresponding with the improvement in his symptoms.
His virus levels increased again, as did his symptoms, when the first course of the treatment ceased, but the effect of the second course of Remdesivir was even more rapid and complete.
By day 64, he no longer tested positive for the coronavirus.
"Our patient's unusual condition gave us a rare insight into the effectiveness of Remdesivir as a treatment for coronavirus infection," said Nicholas Matheson from the University of Cambridge.
"The dramatic response to the drug -- on the repeated challenge -- suggests that it can be a highly effective treatment, at least for some patients," Matheson added.
The researchers suspect that Remdesvir is likely to be most beneficial when administered early in infection, before the virus is able to trigger a potentially catastrophic immune response.
