There was a notable absence last week when U.S. Health and Human Services Secretary Robert F. Kennedy Jr. announced in a 58-second video that the government would no longer endorse the COVID-19 vaccine for healthy children or pregnant women. The director of the CDC — the person who typically signs off on federal vaccine recommendations — was nowhere to be seen. The CDC, a $9.2 billion-a-year agency tasked with reviewing life-saving vaccines, monitoring diseases and watching for budding threats to Americans' health, is without a clear leader.