In both countries, the number of daily deaths peaked in January—3,352 on Jan. 12 in the U.S. and 1,248 on Jan. 23 in the U.K. Since then, the U.S. count has declined 72%—which sounds impressive until you put it up against Britain’s 96%. U.K. deaths now average 47 a day. The U.S. figure, 938, is 20 times as high in a country less than five times as populous.

Many public-health experts thought the U.S. should take the “one dose is better than none” approach, including Ashish Jha of Brown University, Robert Wachter of the University of California and Christopher Gill of Boston University. Even Michael Osterholm of the University of Minnesota, a member of President Biden’s Covid task force known for speaking his mind, suggested delaying second doses. “We could get more of our over-65 age group vaccinated,” he told the Star Tribune. “I think the data will support that actually is a very effective way to go.”

But Anthony Fauci publicly disagreed. On one occasion, Dr. Fauci warned of “the danger” that could come from focusing on the first dose. And at a Feb. 19 White House briefing Dr. Fauci played down a single-dose study from Israel. White House senior adviser Andy Slavitt chimed in, telling reporters, “We’re not going to be persuaded by one study that happens to grab headlines.”