For two years, the coronavirus killed Americans on a brutal, predictable schedule: A few weeks after infections climbed so did deaths, cutting an unforgiving path across the country.

But that pattern appears to have changed. Nearly three months since an ultra-contagious set of new Omicron variants launched a springtime resurgence of cases, people are nonetheless dying from Covid at a rate close to the lowest of the pandemic.

The spread of the virus and the number of deaths in its wake, two measures that were once yoked together, have diverged more than ever before, epidemiologists said. Deaths have ticked up slowly in the northeastern United States, where the latest wave began, and are likely to do the same nationally as the surge pushes across the South and West. But the country remains better fortified against Covid deaths than earlier in the pandemic, scientists said.

Because so many Americans have now been vaccinated or infected or both, they said, the number of people whose immune systems are entirely unprepared for the virus has significantly dwindled.