The UK has been granted ethical approval to commence a human challenge trial this month that involves dosing up to 90 healthy, young, adult volunteers with SARS-CoV-2 in the hopes of understanding more about COVID-19 and accelerating vaccine development.
The primary endpoint for this study is to identify the smallest amount of virus needed to cause infection. Participants will receive a very low dose of a SARS-CoV-2 strain developed by UK scientists based on the original strain that has been circulating the globe since January 2020. If none of the volunteers become affected, scientists will seek permission to use higher and higher doses until they identify the minimal dose necessary to infect most people.
Once an appropriate dose has been identified, a small number of volunteers could be given vaccine candidates—all of which have been proven safe in clinical trials. They will then be exposed to COVID-19 in the hopes of helping to identify the most effective vaccines.
For vaccines still in the mid-stages of development, this study can identify the most promising ones, ultimately helping decide which should move forward in the clinical trial process. For those already in Phase 3, the human challenge study can play a role in furthering our understanding of if/how these vaccines prevent COVID-19 transmission.
The Human Challenge Study will also help scientists and doctors understand how the immune system reacts to COVID-19 and identify factors that influence how the virus is transmitted and how it passes so successfully from one person to another.
Safety concerns
The most important safety step of this trial is to select participants at the lowest risk. The UK is currently looking for up to 90 healthy volunteers aged 18 to 30, who will be compensated for their time. Study investigators say they chose the strain they did because it has been shown to be of low risk to young healthy adults.
According to the UK, the studies will be conducted in a safe and controlled environment, with doctors and scientists closely monitoring all volunteers 24 hours per day.
“Our number one priority is the safety of the volunteers,” said Chris Chiu, a professor at Imperial College London and lead researcher of the study. “My team has been safely running human challenge studies with other respiratory viruses for over 10 years. No study is completely risk free, but the Human Challenge Study partners will be working hard to ensure we make the risks as low as we possibly can.”
Backed by a £33.6 million UK government investment, the Human Challenge Study is a partnership between the government’s Vaccines Taskforce, Imperial College London, the Royal Free London NHS Foundation Trust and hVIVO, a clinical services company that has pioneered viral human challenge models.
“Data from this study will immediately facilitate the challenge model to be used for vaccine efficacy testing as well as to answer a wide range of fundamental scientific questions that are not feasible with traditional field trials, such as exactly what type of immunological response is required to confer protection from re-infection,” said Andrew Catchpole, Chief Scientific Officer at hVIVO.
The study will begin within a month, and results are expected by June/July 2021.