LONDON – The U.K. will become the first country to stage a human challenge trial in which volunteers are deliberately infected with SARS-CoV-2, as a fast route to assessing the effectiveness of COVID-19 vaccines, and to build understanding of what an effective immune response looks like. The contract research organization Open Orphan plc said it is in advanced negotiations with the U.K. government and other partners for the studies, which are expected to be formally announced next week.