LONDON—U.K. researchers plan to start infecting healthy volunteers with tightly controlled doses of the coronavirus in early 2021 in what they called a first-of-its-kind effort to more rapidly gauge the effectiveness of multiple vaccines against Covid-19.
The plans for so-called human-challenge trials target 18- to 30-year-olds who have been free of Covid-19 symptoms and show no other risk factors such as heart disease or diabetes, said the researchers, led by infectious-disease experts at Imperial College London, who are overseeing the effort.
The goal is to test how effective vaccines are in warding off infection and symptoms and to study in detail how participants’ immune systems respond. Plans are to start at a clinical site at London’s Royal Free Hospital, part of the state-funded National Health Service, and eventually expand the study to other sites nationwide, researchers said.
Scientists around the globe for months have debated whether deliberately infecting healthy people with the virus that causes Covid-19 is too high risk and therefore unethical.
Some researchers argue that the severity of the pandemic, including deaths and economic toll, justifies more-aggressive trial methods. But others say there are too many unknowns: Seemingly young, healthy people sometimes suffer extreme Covid symptoms, and there is no proven treatment for subjects who fall seriously ill.