Britain became the first country in the world on Wednesday to give the go-ahead for human challenge trials in which volunteers will be deliberately exposed to Covid-19 to advance research. The trial, due to start within a month, will see up to 90 healthy volunteers aged between 18 and 30 exposed to the smallest amount of the virus needed to cause infection.

Volunteers will be screened for possible health risks, and kept in quarantine for close monitoring for at least 14 days in a specialist unit at London’s Royal Free Hospital. “The absolute priority, of course, is the safety of volunteers,” said Peter Openshaw, a professor of experimental medicine at Imperial College London, which is co-leading the project with the UK government’s vaccines task force and the clinical firm hVIVO.

Volunteers will get compensation of around £88 per day for the duration of the study, which will also involve follow-up monitoring for a year, said the team of Imperial’s Chris Chiu, the trial’s chief investigator. To make the trial safe, the version of the SARS-CoV-2 virus circulating in England since March 2020 will be used, rather than a new variants, they said.

Scientists have used human challenge trials for decades to learn more about diseases such as malaria, flu, typhoid and cholera, and to develop treatments.