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There are a significant number of studies under way into potential treatments for Covid-19.

And some progress has been made in the search for effective medicines.

What work is being done to find treatments?

More than 150 different drugs are being researched around the world. Most are existing drugs that are being trialled against the virus.

 The World Health Organization (WHO) has launched the Solidarity trial aimed at assessing the most promising treatments

 The UK says its Recovery trial is the the world's biggest, with more than 11,000 patients taking part. One of the drugs it is looking at - dexamethasone - has been shown to help save the lives of patients seriously ill with coronavirus.

 And multiple research centres around the world are attempting to use survivors' blood as a treatment

What types of drugs might work?

There are three broad approaches being investigated:
 Antiviral drugs that directly affect the coronavirus's ability to thrive inside the body
 Drugs that can calm the immune system - patients become seriously ill when their immune system overreacts and starts causing collateral damage to the body
 Antibodies, either from survivors' blood or made in a lab, that can attack the virus

What are the most promising coronavirus drugs?

Dexamethasone, the first drug shown to save the lives of people with Covid-19, has been hailed as a breakthrough.

Initial findings showed the low-cost steroid cut the risk of death by a third for patients on ventilators and a fifth for those on oxygen.

Coronavirus infection triggers inflammation as the body tries to fight it off.

This can prompt the immune system to go into overdrive, and it's this reaction that can prove fatal. Dexamethasone damps down this response.

 What is dexamethasone and how does it work?

Clinical trials of remdesivir, an antiviral drug originally developed to treat Ebola, have also been encouraging.

A US-led trial of more than 1,000 people worldwide found remdesivir cut the duration of symptoms from 15 days to 11. Some were given the drug and others were given a placebo (dummy) treatment.

It is one of the four drugs in the Solidarity trial and its manufacturer, Gilead, is also organising trials.

But, although remdesivir may aid recovery - and possibly stop people having to be treated in intensive care - studies have so far not given any clear indication whether it can prevent deaths from coronavirus.

It is thought that antivirals may be more effective in the early stages, and immune drugs later in the disease.

The UK government has made both dexamethasone and remdesivir available on the NHS.

However, the US has bought almost all of Gilead's forthcoming supply of the drug. The Department of Health and Human Services says it has secured 500,000 doses, which amounts to 100% of Gilead's production in July, 90% of it in August and 90% in September.

Gilead has also donated an unknown quantity of remdesivir to South Korea.

Can HIV drugs treat coronavirus?

There has been much talk, but little evidence, that a pair of HIV drugs - lopinavir and ritonavir - could be effective at treating coronavirus.

There has been some evidence they can work in the laboratory, but studies in people have been disappointing.

The combination did not improve recovery, reduce deaths or lower levels of the virus in patients with serious Covid-19.

However, as the trial was conducted with extremely sick patients (nearly a quarter died) it may have been too late in the infection for the drugs to work.

Can malaria drugs stop coronavirus?

Malaria drugs are part of both the Solidarity and Recovery trials.

Chloroquine, and a related derivative, hydroxychloroquine, may have antiviral and immune-calming properties. Hydroxychloroquine is also used as a treatment for rheumatoid arthritis, because it can help regulate the immune system.

The drugs were thrust into the spotlight as potential coronavirus therapies, largely because of claims made by President Trump, but there is still limited evidence on their effectiveness.

Early laboratory tests showed it can inhibit the coronavirus, but concerns emerged about its use against the disease.

The UK's Recovery trial, run by the University of Oxford, found that hydroxychloroquine does not work as a treatment for Covid-19, and it was pulled from that trial.

The WHO had previously suspended its global trials of hydroxychloroquine following a large-scale study in the Lancet which found the drug's use can cause heart problems, and actually increased the likelihood of death.

However, that study was subsequently discredited, and on 30 June, the UK's Medicines and Healthcare products Regulatory Agency (MHRA) said that Oxford University can resume its hydroxychloroquine trials.

Researchers are keen to continue exploring whether the drug might prevent infections.

Can survivors' blood treat coronavirus?

People who survive an infection should have antibodies in their blood that can attack the virus.

The idea is you take the blood plasma (the part which contains the antibodies) and give that to a sick patient as a therapy.

The US has already treated 500 patients with what's known as "convalescent plasma", and other countries are getting involved too.

How long until we have a cure?

It is too soon to know when we might have a drug that can treat the coronavirus.

However, we should start to get the results of trials in the next few months. This is much earlier than we will know whether a vaccine (which protects against infection rather than treat it) is effective.

This is because doctors are testing drugs that have already been developed and are known to be safe enough to use, whereas vaccines researchers are starting from scratch.

Some completely new, experimental, coronavirus drugs are also being tested in the laboratory but are not yet ready for human tests.

Why do we need a treatment?

The most obvious reason for wanting a treatment is it will save lives, but it could also allow further lockdown measures to be lifted.

Having an effective treatment would, in essence, make coronavirus a milder disease.

If it stopped people who were admitted to hospital from needing ventilation, then there would be less risk of intensive care units being overwhelmed, so controls on people's lives may not need to be as strict.