https://www.scientificamerican.com/article/human-challenge-trials-will-deliberately-infect-dozens-in-the-uk/

Young, healthy people will be intentionally exposed to the virus responsible for COVID-19 in a first-of-its kind ‘human challenge trial’, the UK government and a company that runs such studies announced on 20 October. The experiment, set to begin in January in a London hospital if it receives final regulatory and ethical approval, aims to accelerate the development of vaccines that could end the pandemic.

Human challenge trials have a history of providing insight into diseases such as malaria and influenza. The UK trial will try to identify a suitable dose of the virus SARS-CoV-2 that could be used in future vaccine trials. But the prospect of deliberately infecting people—even those at low risk of severe disease—with SARS-CoV-2, a deadly pathogen that has few proven treatments, is uncharted medical and bioethical territory.