Long before the COVID-19 pandemic, Robert F. Kennedy Jr. was building up a following with his anti-vaccine nonprofit group, Children’s Health Defense, and became one of the world’s most influential spreaders of fear and distrust around vaccines.

Washington — President-elect Donald Trump is expected to nominate Robert F. Kennedy Jr. to lead the Department of Health and Human Services, according to three sources familiar with the selection. Kennedy has a long record of criticizing vaccines, including spreading misleading claims about their safety.

At an event at his Mar-a-Lago club in Florida, the president-elect said he wanted Gov. Doug Burgum of North Dakota to be his interior secretary. Mr. Trump also praised Mr. Kennedy, who is skeptical of mainstream health recommendations,