When asked about his reasons for taking the drug, Trump emphasised he believed "it's good, adding he "heard a lot of good stories", and that "a lot of frontline workers and doctors" take it".
Until recently 300m chloroquine treatments were given for malaria every year - it is less used now because of resistance and the development of artemisinin drugs.
"And in fact the opposite, warnings have been issued by many authorities regarding the potential side effects of the drug and many countries have limited its use to that of clinical trials or during clinical trials or under the supervision of clinicians in a hospital setting that's specifically for COVID-19, because of a number of potential side effects that have occurred and could occur", Ryan stressed.More news: Iran 'will support' any nation or group that fights Israel
"We really do not know if chloroquine or hydroxychloroquine are beneficial or harmful against COVID-19", said Nicholas White, a University of Oxford professor and the study's co-principal investigator.
The British participants are expected to be among more than 40,000 healthcare workers across the world testing whether chloroquine and hydroxychloroquine can prevent the covid-19 coronavirus. The 3,000 health care workers and first responders in southeast MI selected for the study each received unmarked vials with either a daily dose of hydroxychloroquine, a once-a-week dose, or a placebo.
The second part of the study is a randomized clinical trial which began last month and is now examining nearly 600 health care workers with 25 to 40 added each day.
US President Donald Trump was criticised this week after he said he had been taking hydroxychloroquine, despite warnings it might be unsafe.
There are fears that increasing demand for hydroxychloroquine during the pandemic could reduce supplies of the drug for patients who need it to treat malaria and certain types of arthritis. I happen to be taking it, hydroxychloroquine, right now.More news: Family of slain Saudi journalist Khashoggi forgives those who killed their father
The FDA warned against use of the medication outside hospitals, where the agency has granted temporary authorisation for its use if clinical trials are unavailable.
Since then, several studies have tested the use of hydroxychloroquine to treat coronavirus.
The study was co-authored by the University, Columbia Veterans Affairs Health Care System in SC and the University of SC and conducted among COVID-19 patients hospitalized in U.S. Department of Veterans Affairs hospitals, which provide comprehensive healthcare services to military veterans.
BSMS said: "Laboratory evidence shows that these well-established drugs might be effective in preventing or treating covid-19 but there is no conclusive proof".
President Donald Trump holds his protective face mask as he speaks while touring Ford's Rawsonville Components Plant that has been converted to making personal protection and medical equipment. Sean Conley, said he "concluded the potential benefit from treatment outweighed the relative risks", according to a memo released Monday night.More news: CDC: Keep cleaning surfaces, but coronavirus mainly spreads person-to-person