The first drug to be approved to treat Covid-19, remdesivir, is likely to be a highly effective antiviral against SARS-CoV-2. This is assured by a study carried out in the United Kingdom, which is published in «Nature Communications», in which it is described that the administration of this drug to a patient with Covid-19 and a rare immune disorder achieved a better dramatic improvement in his symptoms and the disappearance of the virus.
Remdesivir became the only drug approved to treat Covid-19. Originally developed to treat hepatitis C and later tested against Ebola, it appeared to be effective against coronavirus. However, in early October, the World Health Organization (WHO) announced in his study Solidarity that the drug did not significantly reduce mortality rates.
But this team of researchers has used a different approach to determine the effects of the drug on a Covid-19 patient. “There have been different studies that support or question the effectiveness of remdesivir, but some of those performed during the first wave of infection may not be optimal for evaluating its antiviral properties,” he says. James Thaventhiran, from the University of Cambridge.
According to this researcher, mortality is due to a combination of factors, which probably include uncontrolled viral replication and, more importantly, the response of the immune system. «A clinical trial that only looks at the impact of remdesivir on mortality will have a difficult time distinguishing between these two factors.. This limits our ability to ask a simple question: How effective is remdesivir as an antiviral?
To answer this question, they 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 therefore fight infections.
The Covid-19 started with fever, cough, nausea and vomiting, and on the 19th he tested positive for SARS-CoV-2. His symptoms persisted and on day 30 he was admitted to the hospital, where supplemental oxygen was administered for breathing difficulties.
In contrast to other cases, the fever and inflammation of the lungs persisted for more than 30 days, but without causing serious respiratory problems or spreading to other organs. The researchers note that this may be due to its inability to produce antibodies; Antibodies fight infection, but they can also damage the body and even lead to serious illness.
He was initially given hydroxychloroquine and azithromycin, but they had little effect. He then began a 10-day remdesivir therapy. Within 36 hours, his fever and shortness of breath had improved and his nausea and vomiting stopped and he no longer needed supplemental oxygen.
This spectacular response was accompanied by a progressive decrease in the levels of C-reactive protein (CRP), a substance produced by the liver in response to inflammation. At the same time, doctors saw an increase in the number of his immune cells known as lymphocytes, and chest scans showed that the inflammation in his lungs was disappearing.. The patient was discharged on day 43.
One week after discharge, the patient again had a fever, shortness of breath, and nausea. He was readmitted to the hospital and given oxygen. She again tested positive for SARS-CoV-2, was found to have lung inflammation, her CRP levels had increased, and her lymphocyte count had decreased.
He again started the 10-day remdesivir treatment. Once again, your symptoms improved rapidlye, her fever dropped and supplemental oxygen was withdrawn. His CRP and lymphocyte count normalized. After further treatment with convalescent plasma, he was discharged three days later and no longer has symptoms.
The study shows that the patient’s virus levels progressively decreased during their first cycle of remdesivir, corresponding to their improvement in symptoms, but when therapy was stopped, their virus levels rose again. However, the effect of second cycle of remdesivir was even faster and complete.
It is very likely that the patient’s inability to clear the infection without antiviral medication is due to his lack of antibodies. However, there are other immune cells that help fight infection, such as CD8 + T cells.
The team found that the patient was able to produce CD8 + T cells that responded to the ‘spike protein’ on the surface of the virus.. While it is insufficient to clear the infection spontaneously, this probably contributed to the shedding of the virus during the second course of remdesivir.
“The unusual illness of the patient gave us a rare insight into the effectiveness of remdesivir as a treatment for coronavirus infection. Response to the drug, on repeated tests, suggests that can be a very effective treatment, at least for some patients ”, explains Nicholas Matheson of the University of Cambridge.
The team further suspects that remdesivir is likely to be most beneficial when given early in the infection, before the virus can trigger a potentially catastrophic immune response.
“The fact that our patient could not fight the disease without treatment suggests that the antibodies contribute to the control of SARS-CoV-2. But, paradoxically, this lack of antibodies may also have prevented his Covid-19 from becoming life threatening, because he had no antibodies to trigger a harmful immune response, ”they write in their work.
And they conclude: «All this suggests that treatments should adapt to individual patients. Taking this approach more broadly could further clarify how best to use remdesivir for clinical benefit. ‘