Robert F. Kennedy Jr. also disclosed that he had reached at least one settlement agreement with a company or individual that has accused him of “misconduct or inappropriate behavior.”

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., the nominee to lead the Department of Health and Human Services, made disputed claims before the Senate Committee on Health, Education, Labor and Pensions.

In a scathing letter to lawmakers weighing Robert F. Kennedy Jr.’s nomination for health secretary, Ms. Kennedy called her cousin unfit for the job and a “predator” who led family members to addiction.

Mr. Kennedy appears to have most Republicans behind him as he seeks the job of health secretary, though he couldn’t escape his past stances on vaccines and abortion.

Robert F. Kennedy Jr., who has taken different positions on the issue, has pledged to promote President Trump’s anti-abortion agenda in a bid to get confirmed as health secretary.

Dr. Anthony S. Fauci, who was one of the nation’s top health officials for decades, had received death threats during the coronavirus pandemic. He has hired his own security detail.

Scientific meetings were canceled, and research data on the bird flu outbreak was delayed, amid confusion over the directive.

Public health experts say U.S. withdrawal from the W.H.O. would undermine the nation’s standing as a global health leader and make it harder to fight the next pandemic.

In a wide-ranging interview, Xavier Becerra, President Biden’s health secretary, defended his tenure and hinted that he might run for governor of California.

There are an estimated 300,000 polio survivors in the United States. For some, the nomination of Robert F. Kennedy Jr. as health secretary is reviving their painful memories.

Almost 24 million Americans have signed up for plans offered under the Affordable Care Act, driven by subsidies that are expiring and that Congress may not renew.

The administration is committing an additional $306 million toward battling the virus, and will distribute the money before President-elect Donald J. Trump takes office.

Jimmy Carter redefined what a president can do after departing the White House, leaving a lasting imprint through his work overseas, particularly in the realm of public health.

Jimmy Carter’s daughter had an extraordinary and well-documented childhood in the White House. Since then she has for the most part lived a very private life.

The president-elect has promoted the theory for more than a decade and said on Sunday that he was “open to anything” to address a nationwide rise in autism.

© Kenny Holston/The New York Times