Researchers in the United Kingdom plan to begin intentionally infecting a small batch of healthy young people with the novel coronavirus in January as part of a first “human challenge trial,” according to an announcement Monday.
The plan has not yet been approved by the Medicines and Healthcare Regulatory Agency (MHRA), which regulates clinical trials in the UK, and outside experts have had mixed reactions to the announcement so far.
Nevertheless, the UK government is planning to invest $43.4 million (33.6 million pounds) in the trials. Researchers meanwhile are preparing to recruit an initial 30 to 50 people, aged 18 to 30, who have no underlying health conditions. Those conditions include diabetes, heart disease, or obesity, all of which would put them at greater risk of the pandemic coronavirus, SARS-CoV-2, and the disease it causes, COVID-19.
The first phase of the trial will try to determine the smallest number of virus particles necessary to spark an infection. Participants will stay in a secure area of London’s Royal Free Hospital for the whole of the trial and will be monitored for weeks before release. If all goes to plan, the researchers will move forward with testing candidate vaccines and therapies in people purposefully exposed to the virus. So far, no specific experimental vaccines are lined up for the trials, though.
While the plans and the regulatory review move forward, experts have expressed both support for the effort and doubts about its usefulness.
On the one hand, human challenge trials are a firmly established tool in infectious disease and medical research. By deliberately infecting people with a dangerous germ in a controlled trial, researchers can carefully study critical aspects of infection that are difficult if not impossible to examine in real-world cases. For instance, how many virus particles does a person need to get in their nose to trigger an infection? What is the immune system up to after a hefty dose of virus but before a person gets sick—or, perhaps, doesn’t get sick?
Such trials may also offer a faster, safer way to test experimental therapies and vaccines than standard trials. To test a vaccine, for instance, researchers often recruit tens of thousands of people; some will get the experimental vaccine, and some will get a placebo. Then researchers wait for the disease to spread around as it naturally does, while tallying the number of people infected in both the vaccinated and the unvaccinated group. This process can take weeks or months, depending on the state of outbreaks and how quickly the disease is spreading in an area. In the end, if there are significantly fewer infections in the vaccinated group, it might suggest the vaccine is protective. But having a large number of people in each group is critical because researchers don’t know how many people in either group have actually been exposed to the disease. The larger group sizes reduce the…