April 19, 2021

expert reaction to launch of human challenge trial to study immune response in people who have already had COVID-19 infection

Researchers from the University of Oxford have launched a human challenge trial which aims to find out what kind of immune response can prevent people from being re-infected with SARS-CoV-2.

This Roundup accompanied an SMC Briefing.

Prof Chris Chiu, Clinical Reader & Honorary Consultant in Infectious Diseases, Imperial College London, said:

“We are very pleased that the Oxford study, on which we are collaborating closely, is to go ahead.  By bringing together the findings from our initial SARS-CoV-2 human challenge study in people who have previously not had COVID-19 with those from this study, larger and more broad-ranging questions can be addressed.  In particular, we will define how re-infection differs from a first infection with this virus, which may have important implications for how the pandemic is managed going forward as more people develop immunity.  Furthermore, validating the immune markers that are associated with protection (which is one of the main aims of this programme) is critically important for vaccine development and public health planning.  By using the same challenge virus and procedures between the two studies as well as sharing our expertise and experience to maximise participant safety, we anticipate directly comparing results to better address these unknowns.”

Prof Gary McLean, Professor in Molecular Immunology, London Metropolitan University, said:

“This is a really important and interesting challenge study that should go some way towards defining the viral and immunological parameters and further understanding of SARS-CoV-2 reinfections.”

Prof Lawrence Young, Virologist and Professor of Molecular Oncology, Warwick Medical School, University of Warwick, said:

“Human challenge studies have a long history of being able to generate important information about infections under strictly controlled conditions as well as allow the efficacy of vaccination to be accurately assessed.  Such studies can find out find out how much virus is needed to infect an individual, provide detailed information on the dynamics of virus replication and spread, and also permit more intensive study of the body’s immune response to infection and vaccination.

“This new study will investigate what happens when an individual who has recovered from infection with SARS-CoV-2 is subsequently re-exposed to the virus.  It will determine what dose of virus is needed to re-infect after natural infection, how the immune system responds and what this means for the generation of protective immunity.  An important aspect will be determining how long protection from symptomatic infection lasts after natural infection and what aspects of immunity are responsible for this protection.

“This study differs from the challenge trial at Imperial College which is infecting naïve 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.  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 on-going design of vaccines and the development of anti-viral therapies.”

Declared interests

None received.