Scott Atlas, a Trump Coronavirus Adviser, Resigns

But that did not stop Dr. Atlas. In mid-November, he called on people in Michigan to “rise up” against coronavirus restrictions. The state’s governor, Gretchen Whitmer, who had faced death threats and a thwarted kidnapping attempt over the restrictions, denounced him as “incredibly reckless.”

But in his resignation letter and the accompanying tweet, Dr. Atlas defended himself.

“We also identified and illuminated early on the harms of prolonged lockdowns, including that they create massive physical health losses and psychological distress, destroy families and damage our children,” he wrote.

“And more and more,” he added, “the relatively low risk to children of serious harms from the infection, the less frequent spread from children, the presence of immunologic protection beyond that shown by antibody testing, and the severe harms from closing schools and society are all being acknowledged.”

Inside the administration, Dr. Atlas clashed in particular with Dr. Anthony S. Fauci, the government’s top infectious disease specialist, and Dr. Deborah L. Birx, the coronavirus response coordinator.

While Dr. Atlas was playing down the necessity of wearing masks, Dr. Birx was traveling the country preaching the opposite. She implored governors and public health officials in hard-hit states to take more aggressive steps. The two also clashed repeatedly in private.

But Dr. Atlas’s disagreements with Dr. Fauci were more visceral — and more public.

After the election, Dr. Atlas accused Dr. Fauci of being a “political animal” who changed his assessment of the threat of the pandemic after it became clear that Mr. Trump had lost. Dr. Fauci replied in kind.

“I don’t want to say anything against Dr. Atlas as a person, but I totally disagree with the stand he takes,” he said recently on the “Today” show on NBC, after Dr. Atlas’s comments about Michigan. “I just do, period.”