Robert F. Kennedy, President Trump’s nominee for health secretary, vigorously defended his views on vaccines, and a key senator still has clear doubts.

Robert F. Kennedy Jr.'s long record of doubting the safety of childhood vaccinations persisted as a flash point for him ...

Robert F. Kennedy Jr.'s long record of doubting the safety of childhood vaccinations persisted as a flash point for him Thursday in a confirmation hearing where senators, including a key Republican, ...