Researchers in the U.K. are looking for volunteers who have already had COVID-19 for a "challenge study" that will deliberately reexpose them to the novel coronavirus.
The goal of the study is to understand what immune response is needed to protect against reinfection with COVID-19, according to a statement from the University of Oxford, which has received approval to conduct the trial.
"If we could understand, in this really careful controlled way, exactly what kind of immune response is needed for protection [against reinfection], then we will be able to look at people who have natural infection and say whether or not they're protected" against another infection, study chief investigator Dr. Helen McShane, a professor of vaccinology at the University of Oxford, said in a video about the study.
In a challenge study, people who are at low risk of serious outcomes are intentionally exposed to a pathogen in a controlled lab environment. Earlier this year, other researchers in the U.K. began challenge studies in people who hadn't been infected with COVID-19, deliberately exposing them to very small doses of the novel coronavirus SARS-CoV-2.
For the new study, the researchers are recruiting healthy people ages 18 to 30 who were infected with COVID-19 at least three months prior to entering the study and have antibodies against the novel coronavirus, according to The Guardian.
The study will have two phases. The first phase, which will include 24 volunteers, aims to determine the lowest dose of SARS-CoV-2 that can cause an infection while producing little or no symptoms in the volunteers.
"We start with a really, really small amount of the virus … and we check that that's safe," and then increase the dose if necessary (if it's too low to cause an infection in any of the volunteers), McShane said in the video.
"Our target is to have 50% of our subjects infected but with no, or only very mild, disease," McShane told The Guardian.
The second phase will involve another 10 to 40 participants who will receive the dose determined in the first phase. The researchers hope to learn what levels of antibodies, T cells and other immune system components protect against reinfection.
After being exposed to the virus, all of the participants will be quarantined for 17 days and monitored closely. They will undergo numerous tests, including CT scans of their lungs and MRIs of their hearts, the researchers said.
Any participants who develop symptoms of COVID-19 will be treated with Regeneron's monoclonal antibodies, which have been shown to reduce the risk of hospitalizations from COVID-19.
The participants will be followed for at least eight months after they recover from their second infection. Each participant will receive nearly $7,000 (£5,000) for being included in the study, The Guardian reported.
The first phase of the study is expected to start this month, and the second phase is expected to begin in the summer, the researchers said.
Originally published on Live Science.