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UK trial studies ex-Covid patients who are exposed to the virus again

LONDON British scientists yesterday launched a trial that will deliberately expose participants who have already had Covid-19 to the coronavirus again to examine immune responses and see if people get reinfected.

"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 Dr Helen McShane, a University of Oxford vaccinologist and chief investigator on the study.

She added that the work would help understanding of what immune responses protect against reinfection.

Scientists have used human challenge trials for decades to learn more about diseases such as malaria, flu, typhoid and cholera, and to develop treatments and vaccines against 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 per cent of participants, while producing few to no symptoms.

A second phase, starting in the summer, will infect different volunteers with that standard dose.

In phase one, up to 64 healthy participants, aged 18 to 30, who were infected with coronavirus at least three months ago will be reinfected with the original strain of Sars-CoV-2.

They will then quarantine for at least 17 days and be monitored, and anyone who develops symptoms will be given Regeneron monoclonal antibody treatment. - REUTERS

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