London, May 21 : A trial to see whether two anti-malarial drugs -- chloroquine, hydroxychloroquine -- could prevent the novel coronavirus has begun in the UK's Brighton and Oxford. The first UK participants in the global trial are being enrolled on Thursday at the Brighton and Sussex University Hospitals and the John Radcliffe Hospital in Oxford, reports the BBC. They will be given either hydroxychloroquine or a placebo for three months. These are the first of a planned 25 UK sites, with results expected by the end of the year. The trial is open to anyone delivering direct care to coronavirus patients in the UK, as long as they have not been diagnosed with COVID-19. It will test whether the drugs can prevent healthcare workers exposed to the virus from contracting it. One of the study's leaders, Professor Nicholas White at the University of Oxford said: "We really do not know if chloroquine or hydroxychloroquine are beneficial or harmful against COVID-19." But, he said, a randomised controlled trial such as this one, where neither the participant nor the researchers know who has been given the drug or a placebo, was the best way to find out. "A widely available, safe and effective vaccine may be a long way off," the BBC quoted Professor Martin Llewelyn from Brighton and Sussex Medical School, who is also leading the study. "If drugs as well-tolerated as chloroquine and hydroxychloroquine could reduce the chances of catching COVID-19, this would be incredibly valuable." /IANS