London is to host the world’s first Covid-19 human challenge trials — in which healthy volunteers are deliberately infected with coronavirus to assess the effectiveness of experimental vaccines, the Financial Times has reported. The UK government-funded studies are expected to begin in January at a secure quarantine facility in east London. According to the report. Volunteers will be inoculated with a vaccine and a month or so later receive a “challenge” dose of Sars-Cov-2, the virus that causes Covid-19, under controlled conditions. About 2,000 potential volunteers have signed up for challenge studies, the report added.