What's behind the FDA's controversial strategy for evaluating new COVID boosters

The U.S. Food and Drug Administration is using a controversial strategy to evaluate the next generation of COVID-19 boosters.

The approach is stirring debate as the agency works to make new, hopefully improved, boosters available in September to help prevent severe disease and save lives in the fall and winter.

For the first time, the FDA is planning to base its decision about whether to authorize new boosters on studies involving mice instead of humans.