As more Covid-19 vaccines become available in the U.S., it is getting tougher to run large clinical trials to test a new vaccine’s ability to prevent disease because people are less willing to take a placebo–forcing drugmakers and researchers to look for workarounds as they vet the next generation of shots and test new uses for authorized ones.
One potential workaround would be to determine what level of immune response a vaccine has to trigger to protect people from the coronavirus, as measured in blood samples, and to use that information to create smaller, faster and less-expensive clinical trials.
Instead of requiring tens of thousands of volunteers and…
