Despite the fast rollout of vaccines, more than 60,000 people are dying each week from Covid-19.
The need for improved treatments is as great as ever.
As reported in The National, prophylactic or preventative drugs that could be administered in the early stages of infection are being trialled by some of the world’s major pharmaceutical companies.
During later stages of infection, including cases where patients have become seriously ill and are admitted to hospital, a number of treatments are available.
These are typically drugs that have previously been authorised to treat other conditions, but are being “repurposed” to combat Covid-19. Such repurposing is faster than developing all-new drugs.
Here we look at some of the drugs and consider what may be available in future.
What drugs are being used against Covid-19?
Among the most successful and affordable have been corticosteroids like dexamethasone, which an estimate earlier this year suggested had saved one million lives during the pandemic.
This anti-inflammatory drug dampens down the immune system, preventing it from overreacting and releasing excessive amounts of chemicals called cytokines in a process known as the “cytokine storm”. This can cause organ failure and death.
“Corticosteroids like dexamethasone have a huge impact if you give them at the right time,” said Prof Paul Hunter, a professor in medicine and an infectious diseases specialist at the University of East Anglia in the UK.
“If you give dexamethasone too early, you make people more sick. It knocks the body’s immune system and it cannot overcome the virus. If you give it at the right time, you make them less sick.”
Another key class of drugs are monoclonal antibodies, which are identical antibodies produced artificially in large numbers.
Among them is tocilizumab, a repurposed rheumatoid arthritis drug, which also targets the cytokine storm by inhibiting the action of a cytokine called Interleukin-6, and may be given alongside a corticosteroid like dexamethasone.
Antiviral monoclonal antibodies
While some monoclonal antibodies dampen down an excessive immune response, others target the virus itself.
One such treatment has been developed by Regeneron Pharmaceuticals and Roche. Administered to Donald Trump after he contracted Covid-19 when he was president in October, this contains two monoclonal antibodies and aims to stop the coronavirus attaching to receptors on the surface of cells in the respiratory system.
Bamlanivimab, also a monoclonal antibody, may also be given, alongside another drug, to prevent severe disease. Like the Regeneron treatment, it targets the spike protein and aims to prevent the coronavirus entering human cells.
Another monoclonal antibody treatment to target the spike protein is sotrovimab. Produced by the British pharmaceutical giant GlaxoSmithKline and the California-based Vir Biotechnology, it was approved by regulators in Europe, the US and the UAE in May and has been widely used in the Emirates.
Three months after what GSK staff recalled as a “lights-went-on moment”, the UAE became the first country to receive a shipment of the drug, after it proved to be highly effective at limiting severe illness.
Given intravenously, it has been found in trials cited by the European Medicines Agency to reduce the risk of hospitalisation and death by 85 per cent.Dr Averyan Vasylyev, GSK’s medical affairs director in the Gulf, said: “From a medical point of view, it’s like a perfect medicine.”
Not all drugs have convinced regulators or clinicians
Some drugs have offered initial promise, only to disappoint in trials, among them an antimalarial drug called hydroxychloroquine.
An analysis of trials published in the journal Nature in April found the drug was actually associated with higher mortality.
Remdesevir, an anti-viral drug, was approved by the US Food and Drug Administration last year, but a lack of evidence that it is effective led the World Health Organisation to recommend against giving it to Covid-19 patients.
A study by French researchers released this month in The Lancet found “no clinical benefit” from remdesevir in hospitalised patients who had had symptoms for more than seven days and needed oxygen.
What is on the horizon?
There could be more monoclonal antibody treatments on the way, despite the FDA’s rejection this month of an application for an emergency use authorisation (EUA) for lenzilumab, which aims to prevent the cytokine storm.
The drug’s maker, Humanigen, still aims to bring the drug to market and authorisation may be forthcoming once there are trial results with more patients.
Other monoclonal antibody treatments are being trialled, including plonmarlimab, from a company called I-Mab, which also targets the cytokine storm.
A study by University of Cambridge researchers using artificial intelligence screened 2,000 drugs approved for other uses and identified 200 that could be effective against Covid-19.
The research, published two months ago, found that just one fifth of these were in clinical trials, so there are many hundreds of potentially useful drugs yet to be tried.
“I think there’s a long way to go and scope for much more,” said Dr Andrew Freedman, an infectious diseases specialist at Cardiff University in the UK.
“I’ve not seen anything yet that’s going to make a huge difference. We may get more drugs in future – there’s definitely a need for that.”