Caroline Nicolls receives an injection of the Modern Covid-19 vaccine administered by nurse Amy Nash, at Madejski Stadium in Reading, west London, on 13 April 2021.
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LONDON – Researchers at Oxford University announced on Monday the launch of a human challenge trial to better understand what happens when people who have already contracted the coronavirus become infected for the second time.
Researchers will examine what type of immune response can prevent people from being reinfected with Covid-19 and investigate how the immune system reacts to the virus a second time.
Little is currently known about what happens to people who have already had the virus when they become infected a second time.
The test will take place in two phases, with different participants in each phase. The first phase is scheduled to begin this month and the second phase to begin in the summer.
In medical research, human challenge trials are controlled studies that involve deliberately exposing participants to a pathogen or error to study the effects.
“Challenge studies tell us things that other studies can’t do because, unlike natural infection, they are tightly controlled,” said Helen McShane, lead researcher on the study and professor of vaccinology in the Department of Pediatrics. of Oxford University.
“When we re-infect these participants, we will know exactly how their immune system has reacted to the first COVID infection, exactly when the second infection occurs, and exactly how many viruses they have had,” McShane said.
The study is expected to help improve the basic understanding of the virus by scientists and help design tests that can reliably predict whether people are protected.
What happens at each stage?
For the first phase, up to 64 volunteers between the ages of 18 and 30 who have previously been naturally infected will be re-exposed to the virus under controlled conditions.
Researchers will monitor participants ’attention as they undergo computed tomography of the lungs and MRI of the heart while isolating themselves in a specially designed suite for a minimum of 17 days.
Everyone involved must be fit and fit and must have fully recovered from the first Covid infection to minimize the risk.
Trial participants will only be discharged from the quarantine unit when they are no longer infected and are at risk of spreading the disease.
A view of the city of London on a clear day.
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The second phase of the trial will explore two different areas.
“First, we will very carefully define the initial immune response to the volunteers before infecting them. We will then infect them with the dose of virus chosen in the first study and measure the amount of virus we can detect after infection. able to understand what kind of immune responses protect against reinfection, ”McShane said.
“Second, we will measure the immune response at various times after infection so that we can understand what immune response the virus generates,” he added.
The total duration of the study will be 12 months, including a minimum of eight follow-up appointments after discharge.
“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,” said Shobana Balasingam, senior consultant in vaccine research at Wellcome, a charity. which funds the study.
“The findings could have important implications for how we treat COVID-19 in the future and inform not only vaccine development, but also research into the range of effective treatments that are also urgently needed,” Balasingam said. .