Researchers in the UK are gearing up to launch the first coronavirus challenge trial, in which hundreds of participants will be deliberately infected with the disease. If all goes to plan, the trial will launch in January, according to the Financial Times, though scientists are still waiting on regulatory approval from the UK government.
Standard vaccine studies involve thousands of participants, must recruit in areas where contagion is naturally high, and typically take months or even years as researchers wait to see how many people contract the disease. Challenge trials are far quicker, as researchers don’t have to wait to see whether participants contract the virus, though deliberately infecting participants carries a host of other ethical and practical challenges.
The UK challenge trial will test various Covid-19 vaccines against each other, according to the FT. This mirrors how challenge trials are typically used in contemporary medicine: Various strains of vaccine for cholera, malaria, and typhoid are compared to see which is most effective. This helps narrow down the possible vaccine candidates, so resources can be focused on the most effective options. “Given there are more than 100 Covid-19 vaccines in development, you don’t want 100 phase three trials,” Peter G. Smith, co-author of a Journal of Infectious Diseases article on Covid-19 challenge trials, told in May.
The trial will be run by challenge trial company hVivo, a subsidiary of Irish pharmaceutical company Open Orphan, according to the FT, while Imperial College London scientists will lead the research. 1Day Sooner, a group advocating for coronavirus challenge trials, is planning to petition the government to fund a challenge study center that can house up to 200 participants, a spokesperson told .
The government must also approve the effort itself. Before the challenge trial can go ahead, it will need a green light from both the UK Medicines and Healthcare products Regulatory Agency and an independent research ethics committee.
The UK government is currently “working with partners to understand how we might collaborate on the potential development of a Covid-19 vaccine through human challenge studies,” a spokesperson told , while Open Orphan told Reuters the company is in “advanced negotiation with the UK government and other partners for a coronavirus challenge study in the UK.” Open Orphan did not respond to ’s requests for comment about which vaccines would be tested in the trial and whether a placebo would also be used.
A Covid-19 challenge trial is unusual since, unlike typhoid or malaria, there’s no straightforward treatment for participants who do contract the disease. The UK challenge trial plans to use remdesivir. But while there’s evidence the drug alleviates symptoms for some patients, it’s hardly a cure.
Because of the risks involved, 1Day Sooner advocates testing vaccines on relatively young participants with no underlying conditions. This reduces the risk of death in the trial, but it also carries a downside: The trial won’t provide information about how a vaccine works on elderly populations, who are the most at risk from coronavirus. Still, many scientists believe data from challenge trials can inform broader understanding of the virus. “There’s a number of benefits, not just the vaccine but also better understanding of immune responses to the virus,” Peter Horby, professor of emerging infectious diseases and global health at Oxford University told BBC Radio 4’s Today on Thursday (Sept. 24.) Horby is currently running a trial of Covid-19 treatments.
Participants in the UK challenge trial would have to be under close surveillance for around a month after infection. The trial is expected to be held at a secure quarantine site in east London, several people involved in the project told the FT. Around 37,000 people worldwide have told 1Day Sooner they’d be interested in participating in a challenge trial, of which 2,000 are from the UK. Though no volunteers have been called on yet, UK plans are by far the most advanced.