U.K. set to infect volunteers with coronavirus in world's first COVID-19 challenge study

Researchers in the U.K. are set to deliberately infect young, healthy volunteers with SARS-CoV-2. The challenge study, which has £33.6 million ($43.6 million) in government support, could shed light on how people react to the virus and accelerate development of vaccines.

Challenge studies have been used to study vaccines and medicines against influenza and a range of other viral pathogens. The studies entail the infection and close monitoring of volunteers in highly controlled environments. Advocates of the approach have pushed for its use in the study of vaccines against COVID-19 since early in the pandemic in the belief it can accelerate development. 

Now, the U.K. has taken a big step toward running the first COVID-19 challenge study. Working with funding from the U.K. government, specialist contract research organization hVIVO, Imperial College London and The Royal Free Hospital are set to start a challenge study in January.

The timing of the study and nature of its first stage means the move may come too late to have any effect on when vaccines become widely available. Initially, the researchers will focus on identifying the smallest amount of the coronavirus that is needed to cause COVID-19 in up to 90 paid volunteers aged 18 to 30. The study will take place at a specialist Royal Free Hospital unit in London. 

Data from the study, which still requires regulatory and ethical approval, are expected in May. The use of the challenge model to study how vaccines work in humans can only begin once data from the initial characterization stage are available. 

By then, multiple companies may have shown that their COVID-19 vaccines prevent infection in large phase 3 clinical trials, positioning the U.K. and other countries to embark on mass immunization programs. Even so, people involved in the study see value in developing the challenge model.

“First, for the many vaccines still in the mid-stages of development, human challenge studies may help pick out the most promising ones to take forward into larger phase 3 trials. Second, for vaccines which are in the late stages of development and already proven to be safe and effective through phase 3 studies, human challenge studies could help us further understand if the vaccines prevent transmission as well as preventing illness,” Jonathan Van-Tam, the U.K.’s deputy chief medical officer, said in a statement.

While the challenge study may come too late to accelerate vaccine development, it could also arrive too early for the liking of some people. The rate of severe COVID-19 in healthy people aged 18 to 30 is low, but it is plausible that a volunteer will react badly to being infected with SARS-CoV-2. If that happens, the investigators may have limited treatment options.

Gilead’s antiviral remdesivir is available in the U.K.—although data on the molecule are mixed—and researchers have shown dexamethasone helps some patients. Antibodies are nearing approval, but it is unclear how well they work as treatments for COVID-19 or whether they will be available in the U.K. by the time the first stage of the challenge trial starts in January. Holding off on starting the trial could cut the risk to participants but also reduce the value of data generated in the study.   

Other groups are also looking into challenge studies. Belgium invested €20 million in a facility to run challenge studies early in the pandemic and Colorado State University has a U.S. government contract to develop SARS-CoV-2 strains that could be used in human challenge studies.