The UK government has signed a contract for the first human challenge studies for the novel coronavirus, in which healthy volunteers are deliberately infected with the virus in a controlled setting, and some receive an experimental vaccine.
These clinical trials will be a little different from most. For the current Covid-19 vaccine candidates that are in Phase 3 — the final stage of testing — tens of thousands of volunteers are given an experimental vaccine and then released to live their everyday lives; researchers assume that a certain percentage of them will be exposed to the virus naturally.
In a challenge trial, by contrast, participants are deliberately dosed with virus. Proponents of challenge trials say that they are more efficient, requiring far fewer volunteers, likely in the hundreds, because researchers know for certain that everyone will be exposed to the virus, and that they can deliver scientific data more quickly.
Up to 19 volunteers at a time will take part in the tests, to be held at the Royal Free Hospital in London, which houses a Biosafety Level 3 ward. They will be run by hVIVO, a medical research company that specializes in running challenge trials, in partnership with Imperial College London.
Critics worry about exposing people to a virus for which there is no fail-safe treatment, and say that the young, healthy volunteers are not representative of the wider population.
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