Healthy, young volunteers who have previously had Covid-19 will be deliberately exposed to the virus for a second time to see how the immune system reacts.
Oxford University researchers have launched a "human challenge" trial to look at what happens when someone who has recovered from coronavirus is re-exposed to the virus.
They will aim to determine what dose of virus is needed to re-infect after natural infection, how the immune system responds, and what this may mean for developing protective immunity against the disease.
The Wellcome Trust study is expected to start this month after receiving ethics approval and will recruit people aged 18 to 30 who have previously been naturally infected with the disease.