Throughout the pandemic, one of the key questions on everyone’s mind was why some people avoided getting COVID, while others caught the virus multiple times.
Through a collaboration between University College London, the Wellcome Sanger Institute and Imperial College London in the UK, we set out to answer this question using the world’s first controlled “challenge trial” for COVID – where volunteers were deliberately exposed to SARS-CoV-2, the virus that causes COVID, so that it could be studied in great detail.
Unvaccinated healthy volunteers with no prior history of COVID were exposed – via a nasal spray – to an extremely low dose of the original strain of SARS-CoV-2. The volunteers were then closely monitored in a quarantine unit, with regular tests and samples taken to study their response to the virus in a highly controlled and safe environment.
