The peer nations the researchers cited were Austria, Belgium, Denmark, England and Wales, Finland, France, Germany, Israel, Italy, Netherlands, New Zealand, Northern Ireland, Norway, Portugal, Scotland, South Korea, Spain, Sweden, and Switzerland. They calculated the life expectancy figures using official counts for 2019 and 2020, and estimated for 2021 using a validated modeling method.

The approach is “reasonable,” said Prof. Noreen Goldman, a demographer at Princeton University, who was not involved in the research. However, she noted that all estimates were subject to delays in reporting and that it was important to stress that the findings were preliminary.

The U.S. life expectancy estimate for 2021 has not yet been officially reported by the Centers for Disease Control and Prevention, Professor Goldman said, and would not be for another few months at least.

Because life expectancy calculations reflect the conditions in the year they are made, they would be expected to change in coming years. For instance, between 1917 and 1918, during the influenza pandemic, U.S. life expectancy dropped precipitously, by 11.8 years, but quickly rebounded.

Still, Laudan Aron, a senior fellow at the Urban Institute’s Health Policy Center and one of the authors of the study, highlighted the “U.S. health disadvantage,” a term coined in a 2013 report she helped write. “Even Americans who have access to the best of what the U.S. has to offer are not doing well when it comes to health.” They are less healthy than their counterparts in Britain, she said, and structural problems involving systemic racism and inequality can lower positive outcomes for all.

Professor Goldman highlighted research showing that going back to 2000, the life expectancy for a 50-year-old woman in the richest fifth of U.S. counties was lower than what it would be if she lived in the poorest fifth of Japanese jurisdictions. And U.S. life expectancy has largely stagnated and declined since then, she said.

Margot Sanger-Katz contributed reporting.