Covid-19 survivors to be re-exposed to virus for 'challenge study'

About 64 participants will be reinfected with Covid-19 as part of a UK-based study to test immunity.

British scientists on Monday inaugurated a new experiment to examine immune responses of Covid-19 survivors and identify whether or not they could get reinfected. To do so, they will re-expose participants who have already recovered from the virus.

The purpose of this human challenge trial is to monitor immune responses and study the possibility of reinfection post-recovery.

“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,” said Helen McShane, a University of Oxford vaccinologist and chief investigator on the study.

The new trial would provide a better understanding of how the immune system responds and protects the body against reinfection, she added.

Researchers have conducted human challenge trials for decades to learn more about diseases such as malaria, flu, typhoid and cholera, and to develop treatments and vaccines to respond to them.

“The first stage of the trial will seek to establish the lowest dose of the coronavirus needed in order for it to start replicating in about 50% of participants, while producing few to no symptoms. A second phase, starting in the summer, will infect different volunteers with that standard dose,” Reuters reported.

Phase one will be conducted on about 64 healthy participants, aged 18 to 30, all of whom were infected with the coronavirus at least three months ago. This group will be reinfected with the original strain of SARS-CoV-2.

They will then quarantine for at least 17 days while being monitored “and anyone who develops symptoms will receive a monoclonal antibody treatment manufactured by Regeneron Pharmaceuticals Inc.”

Meanwhile, in a separate UK study, scientists are deliberately exposing the virus to volunteers who were not previously infected, after Britain became the first country in the world to give the go-ahead for the dubbed “challenge trials” in humans in February.

“These challenge studies… 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,” Lawrence Young, a virologist at Warwick Medical School in the UK, said in a statement.

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