Jacob Hopkins, 24, tried hard not to get COVID-19 in the months leading up to March 2021, when, if he succeeded, he could be part of a unique experiment in which he was deliberately infected with the virus.

Almost a year earlier, he had put his name on a list of volunteers. Months went by until, on Dec. 23, he finally heard back from someone associated with the experiment. He ended up being the very first volunteer given the infection — patient 1.

As he described it to me, he took a cab to a hospital in London, wearing a mask so he would be sure not to catch COVID-19 at the last minute. He arrived on a Friday, went through a battery of tests over two days, and on Monday, five health care workers came in wearing full PPE, like something out of the movie "Contagion,” pulling in a tank of solution containing SARS-CoV-2.