Human challenge trial aims to study what type of immune response can stop coronavirus reinfection
University of Oxford scientists have launched a year-long trial in which people who have previously been naturally infected by Covid-19 will again be exposed to the virus that causes the disease.
The aim is to study what kind of immune response can stop people from becoming reinfected and how the immune system reacts second time round.
The team said this kind of study, called a human challenge trial, was needed as “not much is known about what happens when people who have already had Covid-19 are infected for a second time”.
Dozens of healthy volunteers between the ages of 18 and 30 will be re-exposed in carefully controlled conditions. The participants will be quarantined in a specially designed hospital suite for a minimum of 17 days under the care of the research team, and will undergo numerous medical tests.
Those who develop any symptoms will be given medical treatment with the Regeneron monoclonal antibody.
Study rationale
“Challenge studies tell us things that other studies cannot because, unlike natural infection, they are tightly controlled,” said Helen McShane, chief investigator on the study. “The information from this work will allow us to design better vaccines and treatments, and also to understand if people are protected after having Covid, and for how long.”
Shobana Balasingam, vaccines senior research advisor at the Wellcome Trust, which is funding the study, said: “This study has the potential to transform our understanding by providing high-quality data on how our immune system responds to a second infection with this virus.”
“Keeping up the pace of scientific research and development, through crucial studies such as this, remain the only way we will truly get ahead of this pandemic and bring it under control.”
External views
Gary McLean, a professor in molecular immunology at the London Metropolitan University, said the study was “really important and interesting” and that it “should go some way towards” defining the viral and immunological parameters of reinfection.
Lawrence Young, a virologist at the University of Warwick, noted that the study differs from another challenge trial at Imperial College London, which is infecting previously uninfected individuals and examining the response to initial infection.
“These challenge studies allow for very precise measurements to be taken under controlled conditions where the timing of initial infection is known,” he said. “They will significantly improve our understanding of the dynamics of virus infection and of the immune response as well as provide valuable information to help with the ongoing design of vaccines and the development of anti-viral therapies.”
An important aspect of the new study, Young said, will be determining how long protection from symptomatic infection lasts after natural infection and what aspects of immunity are responsible for this protection.