Will an anti-Ebola drug be the silver bullet in the fight against COVID-19?

Remdesivir, an anti-viral drug used most recently against the Ebola outbreak, could prove to be very effective in stopping the replication mechanism of the SARS-CoV-2 virus that causes COVID-19, recent research reports have suggested. Once the mass replication of the virus is stopped, the pathogen can be defanged to a large extent. In a recent medical trial, a majority of the limited test subjects showed improvement in condition, which bolsters hope for a quicker path to the cure.

However, there are stumbling blocks and limitations to the kind of clinical trial conducted. Only 53 patients were part of the study, and there were no double-blind, placebo trials—much more authoritative methods where randomised control groups are tested and the remdesivir-administered patients are compared to placebo patients.

The US Centre for Disease Control (CDC) has cited remdesivir as an investigational therapeutic against COVID-19, dubbing it an "investigational intravenous drug with broad antiviral activity that inhibits viral replication through premature termination of RNA transcription, and has in-vitro activity against SARS-CoV-2".

The ICMR said research on its efficacy in the treatment of COVID-19 is a part of WHO's "Solidarity Trial". Head of Epidemiology and Communicable diseases at ICMR, Raman R. Gangakhedkar, said that drug which was used against Ebola virus, according to the researchers, hinders the reproduction of coronavirus which is why they believe that it could be effective in COVID-19 treatment. "Recently reported study on use of remdesivir for COVID-19 treatment is not a clinical trial, but an observational study which found that 68 per cent or two out of three patients after treatment with the drug did not require ventilator support or their need for oxygen support reduced. We will come to know of further developments through the WHO Solidarity Trial, which has an arm which is looking into this," he said.

He further said that remdesivir, developed by Gilead Sciences Inc, a US-based biotechnology company, is not presently available in the country and the government is working on to see if any pharmaceutical company can manufacture it.

What is remdesivir and what do studies claim?

Remdesivir is, in technical terms, an investigational nucleotide analog with antiviral activity both in vitro and in vivo against emerging viral pathogens like Ebola, Marburg, MERS and SARS. In vitro testing conducted by Gilead, which has a patent on the drug, has demonstrated that remdesivir is active against the virus that causes COVID-19. "The safety and efficacy of remdesivir to treat COVID-19 are being evaluated in multiple ongoing Phase 2 and 3 clinical trials. Initial clinical trial data are expected in mid-April," Gilead said in a statement. 

According to the trial, published by the New England Journal of Medicine (NEJM), the patients chosen were those with confirmed SARS-CoV-2 infection who had an oxygen saturation of 94 per cent or less while they were breathing ambient air or who were receiving oxygen support. 

"Of the 53 patients whose data were analysed, 22 were in the United States, 22 in Europe or Canada, and 9 in Japan. During a median follow-up of 18 days, 36 patients (68 per cent) had an improvement in oxygen-support class, including 17 of 30 patients (57 per cent) receiving mechanical ventilation who were extubated. A total of 25 patients (47 per cent) were discharged, and 7 patients (13 per cent) died; mortality was 18 per cent (6 of 34) among patients receiving invasive ventilation and 5 per cent (1 of 19) among those not receiving invasive ventilation."

According to the authors of the study, the observed mortality rate of 13 per cent was demonstrably lower than the death rate of 17 to 78 per cent in China among those severely affected by COVID-19.

“Currently there is no proven treatment for COVID-19. We cannot draw definitive conclusions from these data, but the observations from this group of hospitalised patients who received remdesivir are hopeful," stated Jonathan D. Grein, MD, Director of Hospital Epidemiology, Cedars-Sinai Medical Center, Los Angeles, and lead author of the journal article. “We look forward to the results of controlled clinical trials to potentially validate these findings.”

Daniel O’Day, Gilead’s chairman and CEO, said in an open letter that, “In studying remdesivir, the question is not just whether it is safe and effective against COVID-19 but in which patients it shows activity, how long should they receive treatment and at what stage of their disease would treatment be most beneficial."