By Josephine Mason and Jennifer Rigby LONDON (Reuters) -The world’s first “human challenge” trial in which volunteers were deliberately exposed to COVID-19 to advance research into the disease was found to be safe in healthy young adults, leaders of the study said on Wednesday. The data supports the safety of this model and lays the groundwork for future studies to test new vaccines and medicines against COVID-19 using this kind of trial by the end of this year, the team added. Open Orphan is running the project, launched last February, with Imperial College London, Britain’s vaccines task for…