President Trump claims a drug used against malaria has been approved in the United States to treat the new coronavirus.

Chloroquine is one of the oldest and best-known anti-malarial drugs.

So is the president right and what is known about its effectiveness?

Chloroquine has been around for decades. It's no longer recommended in much of Africa because of the resistance built up to it by the malaria parasites.

Some countries have introduced regulations to curb the use of the drug, but it has remained popular in those with an active private-sector drug market and is sold widely.

This is especially true in Nigeria where there have been reports of high demand for chloroquine in pharmacies leading to shortages, in part fuelled by Mr Trump's statement.

Chloroquine has not been approved for coronavirus

President Trump, at his daily press briefing, claimed that chloroquine had been approved for use in treating the coronavirus by the US Food and Drugs Administration (FDA). That is the body in charge of licensing medicines in America.

"We're going to be able to make that drug available almost immediately. And that's where the FDA has been so great. They've gone through the approval process - it's been approved."

However, the FDA has made it clear it has not been approved for treating those infected with the Covid-19 coronavirus.

"There are no FDA-approved therapeutics or drugs to treat, cure or prevent Covid-19."

However, the FDA does say that studies are under way to see if chloroquine can be effective in the treatment of Covid-19. It also says it has been directed by Mr Trump to set up a large clinical trial to investigate the drug.

At a later briefing, Mr Trump said chloroquine had been approved for "compassionate use". This is where a doctor can give a drug that is yet to be cleared by the government to a patient in a life threatening condition. Doctors are able to prescribe chloroquine in these circumstances, as it's a registered drug.

What is the status of global research?

It's no surprise that chloroquine has been part of the search to help coronavirus patients.

It's well-known, and cheap and easy to produce. In treating malaria patients, the drug has been used to reduce fever and inflammation.

"Chloroquine seems to block the coronavirus in lab studies. There's some anecdotal evidence from doctors saying it has appeared to help," says James Gallagher, BBC health correspondent.

But crucially there have been no complete clinical trials which are important to show how the drug behaves in actual patients, although they are under way in China, the US, UK and Spain.

The World Health Organization says that so far there is no definitive evidence of its effectiveness, but it is part of the continuing trials.

"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," says Prof Trudie Lang, director of The Global Health Network at Oxford University.

Interest in the drug had already been gaining traction online.

Searches for chloroquine have spiked in the past week, according to Google Trends data, and entrepreneur Elon Musk caused a stir when he tweeted out some research into it.

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Panic-buying in Nigeria

The coronavirus pandemic is on the lips of every Nigerian at churches, mosques and schools, reports Daniel Semeniworima, of the BBC's Pidgin service in Lagos.

Many Nigerian households still use tablets containing chloroquine for treating malaria even though it was banned in 2005.

News of a February study in China about the use of chloroquine for the coronavirus had already sparked lively debate in Lagos, so people were stocking up.

Following Mr Trump's reference to chloroquine as a coronavirus treatment, this ramped up and shops and chemists sold out of the drug very quickly.

But the Nigerian Centres for Disease Control has told people to stop taking it.

"The WHO has NOT approved the use of chloroquine for #COVID19 management."Skip Twitter post by @NCDCgov

NCDC✔@NCDCgov

#FactsNotFear@WHO has NOT approved the use of chloroquine for #COVID19 management. Scientists are working hard to confirm the safety of several drugs for this disease.

Please DO NOT engage in self-medication. This will cause harm and can lead to death.#COVID19Nigeria

3,0042:19 PM - Mar 20, 2020Twitter Ads info and privacy3,415 people are talking about thisReport

End of Twitter post by @NCDCgovSkip Twitter post by @Mr_JAGss

Gawat Jubril A.@Mr_JAGss

Hospitals Now Receiving Patients Suffering From Chloroquine Poisoning says Lagos SSA Health @Oreoluwa_Finnih ..... urges people against massive consumption of Chloroquine as a measure to fight Coronavirus. #COVID19 #Covid19Lagos

22311:43 AM - Mar 20, 2020Twitter Ads info and privacy445 people are talking about thisReport

End of Twitter post by @Mr_JAGss

Daniel Semeniworima says people are taking uninformed decisions to stay safe but this is having serious medical consequences.

It's been reported that Lagos is now dealing with a spate of people being poisoned from overdoses of chloroquine.