Vaccine clinical trials in the United Kingdom have come to the point where they need to “challenge” how well the vaccines work by deliberately infecting vaccinated people with SARS-CoV-2, the virus that causes COVID-19.
To do this, the U.K. is investing $43.6 million to determine the smallest dose of the virus strain that will infect the volunteers, and conducting the challenge trials between January and March, 2021. This phase of the clinical trials is open only to about 30 to 50 healthy adults ages 18 to 30. It’s anticipated that some participants might receive a placebo, although that plan hasn’t been finalized.
At least one virologist and vaccine scientist at the University of Maryland Medical Center in Baltimore, Meagan Deming, wonders whether the challenges will yield useful information. “Because such trials are likely to involve only young, healthy people, they might not reveal much about how vaccines could protect those most at risk of severe disease, such as older people and those with conditions such as diabetes,” Nature quoted her as saying.