The Trump administration is at risk of its first major failure as the measles outbreak spreads. Donald G. McNeil Jr., a former New York Times global health reporter, is author of “The Wisdom of Plagues.”

The health secretary has long pushed misinformation about vaccines and played down an outbreak in Texas that has led to the death of a child.

Robert F. Kennedy Jr., secretary of the Department of Health and Human Services (HHS), said the measles outbreak in west Texas is a “call to action,” as he encouraged parents to consider whether to get their children vaccinated. Kennedy, a longtime vaccine skeptic, said the decision to vaccinate is “personal” but defended the efficacy of…