University of Oxford scientists plan to reinfect dozens of adult volunteers with the coronavirus in the second U.K. clinical trial to study deliberate Covid-19 infection in quarantine—this time among people who have already recovered from the virus.
Such “human challenge” trials are controversial because they involve intentionally infecting healthy humans, and the U.K. is the only country so far conducting them with Covid-19, researchers said.
Challenge-trial proponents argue there is no substitute for the precision of controlled studies. They have been used for decades to study diseases including typhoid, malaria and tuberculosis and to develop vaccines. With Covid-19, Prof. [Helen] McShane told journalists in a briefing [recently], “We don’t know whether someone has not been infected because they haven’t been exposed or [because] they have protective immunity.” Controlling exposure will help with those questions, she said.
The first phase of the Oxford-led trials will test virus dosages required for reinfection, administered through the nose. Phase two will chart immune response, including protection via prior infection. No vaccines will be used in either phase.
Volunteers will be tracked for a year. They will be paid around £5,000, equivalent to $6,917, for their time in quarantine and for follow-ups, Prof. McShane said.