"Human challenge" trials of potential COVID-19 vaccines, where volunteers are deliberately infected with the disease, could become a reality in Britain.
It comes after a British biotech firm signed a contract with the government to create and provide strains of the virus.
Preliminary work for the trials, which aim to speed up the process of determining the efficacy of a vaccine candidate, is being carried out by hVIVO, a unit of pharmaceutical services company Open Orphan.
This involves creating a human challenge study model that could be used should such trials gain ethical and safety approval from regulators.
"The model development involves the manufacture of the challenge virus and the first-in-human characterisation study for this virus," the company said.
Supporters of human challenge trials say they are a good way to cut short the often lengthy process of testing potential vaccines on tens of thousands of volunteers in the real world who go about normal life and are monitored to see if they contract the disease or are protected from it.
In these tightly-controlled trials, volunteers are given a vaccine and then about a month later are deliberately infected with the disease under controlled conditions. They are then isolated in a quarantine facility and monitored to see if they become sick or if the vaccine protects them.
Critics say deliberately infecting someone with a potentially deadly disease for which there is currently no effective treatment is unethical.
Any human challenge trials conducted in Britain would have to be approved by the Medicines and Healthcare products Regulatory Agency, the healthcare regulator that looks into safety, ethics and protocol. Any assessment would be carried out after hVIVO completes its preliminary work.
The characterisation study - the first step towards finding the right form and dose of the virus that could be used to deliberately infect participants in future trials - is backed by Imperial College London and will be conducted by hVIVO at a specialist research unit at London's Royal Free Hospital.
The work will be carried out "under the scrutiny of highly trained scientists and medics", hVIVO said in a statement.
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