Covid-19 'Challenge Trial' will purposely reinfect adults.
People who have fought off the Covid-19 virus will be deliberately reinfected in a first-of-its-kind trial at the University of Oxford that may shed light on how to develop more effective vaccines against the pathogen.
Researchers are looking for 64 healthy, previously Covid-infected volunteers from 18 to 30 years old to be studied under controlled, quarantined conditions for at least 17 days, the UK university said Monday. Participants will be infected with the original strain from Wuhan, China and followed for a year.
Initial data from the Oxford study should be available within several months, helping vaccine developers look at levels and types of immunity needed to prevent reinfection, and how long protection persists. Challenge trials, involving deliberate, supervised infections, are seen as particularly helpful for answering questions like these, because they allow scientists to scrutinize the details of how the body confronts the virus and vice versa.
While vaccines and previous infections provide some immune protection against the coronavirus, concerns and doubts remain about how long it lasts. A recent study indicated that as much as 10% of previously infected young adults were reinfected, underscoring the need for effective vaccines to prevent spread, and Pfizer Inc’s chief executive officer has said that booster shots may be needed to maintain the immunity provided by the initial two doses of the company’s shot.
The Oxford study "has the potential to transform our understanding by providing high-quality data on how our immune system responds to a second infection," said Shobana Balasingam, a research adviser at the Wellcome Trust, which is providing funds. The findings could “inform not just vaccine development but also research into the range of effective treatments that are also urgently needed."
One of the goals of the study is to determine how much virus, on average, it takes to infect someone who’s had the virus earlier. In a second phase of the study, a different group of patients will be given that dose and studied for their immune responses, Oxford said.
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 33.6 million pounds ($46.3 million) of UK 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.
Participants who develop Covid symptoms will be treated with an antibody drug from Regeneron Pharmaceuticals Inc that’s been authorized by US regulators, Oxford said. Subjects will only be discharged from the quarantine unit when they are no longer infected and not at risk of infecting others, according to the statement.