Covid-19: After conflicting studies, effectiveness of remdesivir still in question
A US study published this week raised great hope for the effectiveness of the antiviral drug remdesivir for the treatment of patients with Covid-19. But results of a similar study in China seemed to show the opposite.
Dr Anthony Fauci, the director of the US National Institute of Allergy and Infectious Diseases and a prominent member of the White Houses coronavirus task force, is satisfied. Fauci, who oversaw the US study on the effectiveness of the antiviral drug remdesivir, was visibly pleased when he told reporters that "the data shows that remdesivir has a clear-cut, significant, positive effect in diminishing the time to recovery" of Covid-19 patients. Following this conclusion, the New York Times reported that the White House had begun to consider allowing hospitals to administer the drug.
The study that put a smile on Fauci's face was conducted under the auspices of the National Institutes of Health (NIH) on 1,063 patients in the US, Europe and Asia. Beginning on February 21, for every patient who received a placebo, two patients received remdesivir, and preliminary analysis of the results showed that patients treated with Gilead's drug could expect to recover from Covid-19 four days sooner than those who were not. The fatality rate of the disease was also found to be slightly lower for those individuals who received remdesivir.
"Specifically, the median time to recovery was 11 days for patients treated with remdesivir compared with 15 days for those who received placebo," an NIH statement said.
“Although a 31 percent improvement doesnt seem like a knockout 100 percent, it is a very important proof of concept because what it has proven is that a drug can block this virus,” Fauci said at the White House.
This may be the proof that the scientific community has been waiting for. Since the beginning of the Covid-19 outbreak, remdesivir has been considered one of the most promising treatment options while the world waits for a vaccine. What makes it particularly attractive is that it specifically targets the mechanism that allows pathogens such as coronaviruses to "replicate and amplify their viral load in the host body", said Isabelle Imbert, a specialist in antivirals at the University of Aix-Marseille. In addition, remdesivir attacks a process "specific to these viruses and which does not occur naturally in the human body, which makes it less harmful to the organism and improves its benefit-risk ratio", she adds.
Initially developed by Gilead to combat Ebola, the treatment has proven to be effective against the various coronaviruses that have emerged since the early 2000s. "It has produced very encouraging results in tests on animals exposed to SARS (Severe Acute Respiratory Syndrome, which occurred between 2002 and 2004) and MERS (Middle East Respiratory Syndrome, which appeared in 2012)," the French researcher recalled.
That a vast study seems to confirm the hopes placed in remdesivir has not escaped the notice of financial markets. The announcement of the US studys results was enough to cause the stock market index to soar in New York, underlining the importance of this perceived scientific breakthrough in the eyes of investors.
Different results in China
However, perhaps investors should have paid more attention to what was happening in China. On the same day that Gilead and the NIH announced their findings, a team of Chinese researchers published much less encouraging conclusions in the highly respected British medical journal The Lancet. Their experiment, conducted on 237 severely ill patients in 10 hospitals in Hubei province (the region where the epidemic originated), seems to indicate that remdesivir makes little difference. "Unfortunately, our study shows that this treatment does not provide any specific benefit compared to a placebo," wrote Bin Cao, the main author of the article.
So back to square one? Its difficult to decide, because "the two studies seem to be of equal quality", says Stephen Evans, a pharmacoepidemiology researcher in the department of medical statistics at the London School of Hygiene and Tropical Medicine.
Moreover, it seems difficult to compare the studies because information about some of their basic assumptions is lacking. "We don't know, for example, at what stage of the disease the remdesivir was administered in each case and whether there were combinations with other treatments, which could have had major impacts on the results," said Jonathan Stoye, a virologist at the Francis Crick Institute in London.
Furthermore, "the studies carried out on SARS in 2002 showed that the longer it took to use remdesivir, the less effective it was", recalls Étienne Decroly, virologist and director of research at the French National Centre for Scientific Research, speaking to FRANCE 24. In the Chinese experiment, the patients were all "in a serious condition", which could explain why its results are less promising, she says.
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