Since the coronavirus outbreak, much attention has been focused on the rush to find a cure.
So far, doctors have been left relatively powerless when trying to assist patients, although they can give support to help severely-affected people breathe.
Fortunately for most people, our existing immune systems are enough to fight off an infection.
But for those more vulnerable due to age or pre-existing conditions, the need for an effective vaccine is clear. Several trials are already underway.
The development of vaccines is a notoriously long process, however, and is likely to take at least a year.
But what if we have already have a cure, but we just don't know it?
Over recent days there have been some claims that the decades-old anti-malaria drugs, chloroquine and hydroxychloroquine, could help those infected.
The theory has some high-profile backers but it remains a long way from being established fact.
What are chloroquine and hydroxychloroquine?
Both are anti-malaria drugs that have been around for decades and are cheap and easy to produce.
Chloroquine, discovered nearly a century ago, has been used so widely that in parts of Africa it is no longer recommended as an effective anti-malarial due to malaria parasites having built up resistance to it.
Hydroxychloroquine is another drug used to prevent and cure malaria and is also effective in treating people with rheumatoid arthritis.
Unlike with new drugs or vaccines, the side effects of both drugs are well known and they have been proven to be safe in appropriate doses.
Why do people think they could help with coronavirus?
There is some anecdotal evidence that chloroquine and hydroxychloroquine could be effective in treating patients with Covid-19.
In the absence of any proven cure or treatment for the virus, some doctors have turned to other drugs and reported positive results.
Interest has grown online since Elon Musk, the Tesla founder, tweeted about the potential treatments, with Donald Trump, the US president, also touting malaria drugs as a possible “game changer”.
Several trials are already underway, mainly in China, to test chloroquine’s effectiveness against the novel coronavirus.
Early results show that it does seem to cut down the virus’ rate of replication.
While malaria is a parasitic infection, rather than a viral one like coronavirus, it is hypothesised that the drugs’ impact on human cells could help slow the advance of Covid-19, giving the body’s immune system time to catch up.
Pre-clinical trials have also shown the anti-malaria drugs to be effective against other viral infections, such as SARS and MERS.
However, these benefits have not yet been proven in a large-scale trial, which is the only way to show that a drug really works.
Even if they are shown to work in helping people get better, they would not be a vaccine for Covid-19.
"In order to know which therapies could work to treat the viral infection we need to undertake clinical trials to gain the full evidence to know whether they work or not," Professor Trudie Lang, director of The Global Health Network at Oxford University, told the BBC.
According to the World Health Organisation, “there is no evidence that current medicine can prevent or cure the disease”.
What has Donald Trump said?
The US President, who has been holding daily press briefings about the pandemic, has repeatedly promoted the use of the anti-malaria drugs as a potential treatment for coronavirus.
On Friday, he described the drug hydroxychloroquine as a “game changer”, adding, “we’re going to be able to make that drug available almost immediately”.
However, he did acknowledge that he did not know for certain if the drugs would work.
He added: “I’m a smart guy. I feel good about it.” The following day, he said he was “very confident” it could be effective.
He also used his Twitter account promote a study which suggested hydroxychloroquine, combined with an antibiotic, could be an effective treatment, although the research was based on a tiny sample of patients, raising questions over its reliability.
How have people reacted?
The President’s comments have proved controversial, with some accusing him of making irresponsible claims that are not evidence-based.
Indeed, his own officials have been far more sceptical about whether the drugs could prove significant in the fight against Covid-19.
Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases in the US, explained from the same stage as Mr Trump on Friday that there was only anecdotal evidence that the drugs, chloroquine and hydroxychloroquine might be effective.
“The president feels optimistic about something, has feelings about it,” Dr Fauci said. “I am saying it may be effective.”
There is also concern that the President’s comments have caused a rush to buy the drugs, potentially limiting supply for those they are proven to help.
“Rheumatologists are furious about the hype going on over this drug,” Michael Lockshin, of the Hospital for Special Surgery in Manhattan, told The New York Times.
“There is a run on it and we’re getting calls every few minutes, literally, from patients who are trying to stay on the drug and finding it in short supply.”
In a further development, Nigeria has reported two cases of chloroquine poisoning after Mr Trump praised the anti-malarial as a treatment for coronavirus.
Meanwhile, the US Food and Drugs Administration has made clear that the drugs have not been “approved” to treat Covid-19.
Instead, studies are underway and chloroquine can be given to patients for “compassionate use”, a process in the US where a doctor can give a drug that is yet to be cleared by the government to a patient in a life-threatening condition.
