Robert F. Kennedy Jr., head of the Department of Health and Human Services, downplayed the seriousness of an ongoing measles outbreak in Texas, falsely claiming that people had been hospitalized “mainly for quarantine” and misleadingly stating that the situation is “not unusual.

“We have measles outbreaks every year,” he added. Mr. Kennedy has also said in the past that immunizations against measles and some other infectious diseases are unnecessary and risky.