By British scientists today (Monday 19 April) launched a trial which 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 University of Oxford’s “human challenge” trial also hopes to discover what dose of coronavirus is needed to cause a reinfection, and what this may mean for developing protective immunity against the disease.
“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.
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% 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 18-30, 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.
Regular check-ups in the year after reinfection will help establish the immune response generated by the virus – and this could contribute to the creation of better vaccines, and a greater understanding of how long immunity lasts.
The earliest volunteers in the world’s first human challenge trial involving the coronavirus, conducted by Imperial College in London, left quarantine in late March. That trial, which intentionally infected people who hadn’t previously had the virus, was backed by $46.3 million of U.K. government funding.
Critics of challenge trials have pointed out the ethical dangers of infecting people without being sure of its long-term consequences. The Oxford researchers said that all those enrolled will be completely fit, well and recovered from their first Covid infection.
