The trial will open to British participants at hospital sites in Brighton and Oxford It will involve those who are in close contact with patients with proven or suspected COVID-19 LONDON: British health care workers will on Thursday begin taking part in a University of Oxford-led international trial of two anti-malarial drugs to see if they can prevent COVID-19, including one US President Donald Trump says he has been taking. The ‘COPCOV’ study will involve more than 40,000 frontline health care workers from Europe, Africa, Asia and South America to determine if chloroquine and hydroxychloroquine are effective in preventing the novel coronavirus. The drugs have risen to prominence since Trump said earlier this week he was taking hydroxychloroquine as a preventive medicine against the virus despite medical warnings about its use. The trial, led by the University of Oxford with the support of the Mahidol Oxford Tropical Medicine Research Unit (MORU) in Bangkok, will open to British participants at hospital sites in Brighton and Oxford on Thursday and involve those who are in close contact with patients with proven or suspected COVID-19. “We really do not know if chloroquine or hydroxychloroquine are beneficial or harmful against COVID-19,” said the University of Oxford’s Professor Nicholas White, the study’s co-principal investigator who is based at MORU. “The best way to find out if they are effective in preventing COVID-19 is in a randomised clinical trial,“ In Britain, Europe and Africa participants will receive either hydroxychloroquine or a placebo for three months. In Asia they will receive either chloroquine or a placebo. A total of 25 study sites are expected to be open in the UK by the end of June, MORU said, with plans for further sites in Thailand and Southeast Asia, Italy, Portugal, Africa and South America. The results are expected by the end of this year. “We are looking at this with great care and examining all of the evidence that is out there,” Britain’s security minister James Brokenshire told Sky News.