A new day for human challenge trials?

Abie Rohrig, Nir Eyal

Publication Date: 05/21/2022

The world’s first COVID-19 human challenge trial

On 31 March 2022, Killingley et al. published the results from the world’s first COVID-19 human challenge trial, in which 36 healthy volunteers between the ages of 18 and 30 years were intranasally exposed to a low dose of wild type severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Around half (53%) of the volunteers became infected with COVID-19, with researchers finding that the viral load peaked 5 days after inoculation. SARS-CoV-2 was first detectable in the throat, before rising higher in the respiratory tract, where its presence in the nose continued for 10 days. The team found that symptoms develop rapidly, starting on average just 2 days after infection. They also found that lateral flow tests were a reliable indicator of whether or not volunteers were infectious. Six volunteers were given remdesivir after testing positive. No volunteers reported any major negative health outcomes after 180 days, though some reported partial smell disturbance.