I am one of the signatories to an open letter from 1DaySooner on challenge trials sent to Dr. Francis Collins at NIH. A major development announced with the letter is that 1Day Sooner and Oxford’s Jenner Institute are collaborating to prepare viral production for use in challenge trials.The Jenner Institute is the creator of the AstraZeneca produced vaccine, the vaccine farthest along in development.
A key goal of the letter is to encourage the NIH to start its own preparation for challenge trials:
The undersigned urge the U.S. government…its allies, international funders, and world bodies (e.g. the World Health Organization), to undertake immediate preparations for human challenge trials, including supporting safe and reliable production of the virus and any biocontainment facilities necessary to house participants.
Among the signatories are 15 Nobel prize winners including Oliver Hart and Al Roth, Molecular geneticist Mario Capecchi, professor of medicine William G. Kaelin and physician Barry Marshall (who knows a thing or two about volunteer trials.)
As I discussed earlier, since challenge trials restrict the volunteers to be young and healthy, you can’t apply their results directly to the sick and elderly (the external validity problem) but “challenge trials could help us whittle down [candidate vaccines]… to the best two to three, substantially speeding up the vaccine discovery process.” You could also use challenge trials to help figure out the right dosing which is unusually important in the current situation because if a vaccine can work with .5ml instead of 1ml that’s equivalent to doubling the available supply. The Director of the Jenner Institute, Adrian Hill, agrees writing:
We see considerable potential in the use of human challenge studies to accelerate COVID-19 vaccine development, down-select and help validate the best candidate vaccines, and optimise vaccination approaches.
You can read the whole letter here.