In recent days we have seen disappointing results reported from trials of drugs touted as potential treatments for Covid-19.
Doctors have been trying to save the lives of people infected with the coronavirus since last year, and a range of drugs more commonly used to ward off malaria, block viruses and suppress the immune system have all been suggested as possible treatments.
But the results have been inconclusive and the US medical authorities currently say no drug is proven to work against Covid-19.
This anti-viral drug was developed by the US pharma giant Gilead Sciences as a treatment for Ebola.
It was touted as showing early promise in the fight against Covid-19, but there have been confusing reports about its effectiveness in recent days.
Last week the US health news site Stat published enthusiastic comments made in a video chat by scientists at the University of Chicago, which is taking part in phase III clinical trials of remdesivir sponsored by Gilead.
The comments appeared to suggest that doctors had seen promising results for some severely ill patients.
Both the university and Gilead said people should not draw conclusions about the trials before the full data was published.
Scientists have pointed out that in any event, this particular trial is not a randomized double-blind placebo-controlled trial, and so will be of limited value in telling us how effective remdesivir is as a treatment.
Considered the gold standard of medical studies, a placebo-controlled trial would see one group of patients given the drug alongside a control group of patients receiving the same treatment but a placebo instead (“double-blind” means neither patients nor doctors know who has been given the placebo).
Chinese study “underpowered”
There are several trials of this nature in progress around the world. Gilead has provided remdesivir free of charge to researchers but does not control how the studies are done.
The full results haven’t been published yet, but some draft data from a Chinese trial with 237 patients was published, apparently accidentally, on the WHO website on Thursday before being taken down rapidly.
The summary posted on the WHO site said remdesivir was not associated with “a difference in time to clinical improvement” or “clinical or virological benefits”.
Gilead said in a statement that the post “included inappropriate characterizations of the study”, adding: “The study was terminated early due to low enrollment and, as a result, it was underpowered to enable statistically meaningful conclusions.
“As such, the study results are inconclusive, though trends in the data suggest a potential benefit for remdesivir, particularly among patients treated early in disease.”
Experts say we will have to wait for proper data from larger randomised controlled trials later this year to find out whether remdesivir works.
This well-known antimalarial drug, often better known in its variant form hydroxychloroquine, became notorious last month when US president Donald Trump expressed optimism that it could be a “game changer” in the fight against Covid-19.
There has been disappointing news since then about the drug.
Concerns have been raised about a French study that sparked a lot of interest in hydroxychloroquine after reporting dramatic results from a trial of 20 patients.
The International Society of Antimicrobial Chemotherapy, which publishes the journal where the results were first reported, said the article “does not meet the Society’s expected standard, especially relating to the lack of better explanations of the inclusion criteria and the triage of patients to ensure patient safety”.
Another study on 368 patients in a US military veterans’ hospital found an increased risk of death among patients treated with hydroxychloroquine, administered both with and without the antibiotic azithromycin.
The study is the largest of its kind but still falls short of the gold standard for medical evidence. Again, randomised controlled trials of chloroquine are in progress around the world and we will have to wait for proper evidence.
This drug combination has been used successfully to prevent and treat HIV and AIDS. Again, it seemed like a promising Covid-19 treatment.
But a Chinese study reported this week that the treatment had “little benefit” for patients.
The researchers only reported data on 86 patients. Again, much larger and better-designed trials are in progress.
Professor Ian Jones, Professor of Virology at the University of Reading, said: “We are beginning to see a number of early drug trial reports and, generally, the results are disappointing.
“In this case the drugs were a long shot as they were developed for different viruses, not specifically for coronaviruses.”
He added: “Ideally drug treatment would follow an early diagnosis when symptoms are hardly present. So it is too early to give up on Covid drug therapy yet.
“Given at the appropriate time they could still impact disease, improve recovery and limit virus spread. More trials, with drug given at earlier times, are needed.”
Many trials, other drugs
Multiple trials are in progress around the world to test all the drugs we’ve talked about so far.
Scientists are also testing an anti-inflammatory steroid called dexamethasone and beta-interferon, a drug that suppresses the immune system and is used to treat multiple sclerosis.
There are many other potential treatments for coronavirus patients being investigated. In fact, there are more than 300 trials in progress around the world assessing various drugs or combinations.
And of course, clinical trials are also under way for a number of possible vaccines.