UK trial deliberately infects young adults with COVID-19

The study model was shown to be safe and well tolerated in healthy young adults.



The world's first "human challenge" trial, in which healthy young adults were deliberately exposed to COVID-19 to advance research into the disease, was found to be safe, according to the study's leaders. The data supports the model's safety and lays the groundwork for future studies to test new vaccines and medicines against COVID-19 using this type of trial. The project, which began in February 2021, is led by Open Orphan, in collaboration with Imperial College London, the Britain’s 'vaccine task force, and Orphan's clinical firm hVIVO. The trial exposed 36 healthy male and female volunteers, ages 18 to 29, to the original SARS-CoV-2 strain and observed them in a quarantined setting. The volunteers will be monitored for a year after they've been discharged.


There were no serious adverse events, and the human challenge study model was shown to be safe and well tolerated in healthy young adults. Researchers found symptoms appear on average two days after contact with the virus, which is earlier than the widely held belief that the virus has a five-day incubation period. Imperial reported that eighteen volunteers became infected, and 16 of them developed mild-to-moderate cold-like symptoms, such as a stuffy or runny nose, sneezing, and a sore throat. The trial used the lowest dose necessary to infect people, although the team said it was comparable to real-world infections. The researchers will now look at other aspects of the trial, such as why some participants in the final analysis did not become infected despite exposure.