Right after Abie Rohrig turned 18, he told his mom he would be donating a kidney to save a stranger's life. Her answer was no, but he did it anyway. The organ went to a man about his age, and his mom was so inspired she donated a kidney herself. So Rohrig expected her to understand when he told her that, for the benefit of humanity, he may volunteer to become infected with Covid-19. He's one of 22,000+ volunteers, mostly young adults from more than 100 countries, who signed up for a controversial proposal to speed up the development of a vaccine by intentionally infecting dozens of participants. Those who've signed up -- at a new website called 1 Day Sooner -- have all checked a box next to the statement: "I am interested in being exposed to the coronavirus to speed up vaccine development." Bioethicists weigh the pros and cons.