Nature Researchers deliberately infect participants with SARS-CoV-2 in ‘challenge’ trials — but high levels of immunity complicate efforts to test vaccines and treatments.
When Paul Zimmer-Harwood volunteered to be intentionally infected with SARS-CoV-2, he wasn’t sure what to expect. He was ready for a repeat of his first brush with COVID-19, through a naturally acquired infection that gave him influenza-like symptoms. But he hoped his immunity would help him feel well enough to use the indoor bicycle trainer that he had brought into quarantine.
It turned out that Zimmer-Harwood, a PhD student at University of Oxford, UK, had nothing to worry about. Neither he nor any of the 35 other people who participated in the ‘challenge’ trial actually got COVID-19.