If the nation’s largest state is any gauge, American life expectancy in the post-Covid era has not bounced back.

A new analysis published on Wednesday in the medical journal JAMA found that life expectancy in California not only decreased sharply in the peak pandemic years of 2020 and 2021, it remained lower in 2024 than it was in 2019, primarily as a result of causes other than Covid.

Drug overdoses and cardiovascular disease, for example, accounted for a larger proportion of the deficit than Covid as time went on.

“I have to say, I was quite disappointed by our findings,” said Hannes Schwandt, a health economist and economic demographer at Northwestern University, who led the study.

After a pandemic, he said, researchers often expect to see the depressed life expectancy numbers shoot back up and “usually even overshoot for a few years.” That is because the viruses tend to kill the population’s older, sicker people who might have otherwise died in later years.

“Four years after the beginning of the pandemic, for the largest state in the country to still have a deficit — that’s mind-blowing,” he said. “Really quite a tragedy.”

Technically speaking, life expectancy is the estimated life span of a hypothetical cohort of newborns, based on age-specific mortality rates at that time. It is not a prediction for any single individual, but rather an average for the population, based on various health threats faced by different groups.

Earlier research found that life expectancy across the United States had dropped by more than two years between 2019 and 2021 — from 78.8 years to 76.4 years — but had then begun recovering, although not fully, in 2022 and 2023. The national figures for 2024 are not yet available, but California’s vital statistics have been published, which gave researchers an early peek.

The team of experts from an array of American universities used population data from the American Community Survey, an annual sampling conducted by the Census Bureau, along with death data from the California Comprehensive Death Files to do their calculations.

In the half-decade before the pandemic struck, life expectancy in the state showed a slight upward trajectory. It was 81.4 years in 2019, but plummeted with the rest of the country when Covid hit, losing almost three full years by 2021.

As California emerged from the acute phase of the pandemic and life expectancy began to recover, it looked as though the metric plotted on a graph might resemble a V shape, returning as quickly to prepandemic levels as it had dropped. But that was not the case. Instead, the researchers found a life expectancy of 80.54 years in 2024, a deficit of 0.86 of a year compared with 2019.

The researchers also examined demographic trends. They calculated the life expectancy for four income quartiles (based on the median incomes in residential census tracts), as well as for Black, white, Hispanic and Asian Americans as they were reported on death certificates.

People who lived in the poorest neighborhoods experienced more significant decreases in life expectancy during the pandemic than people in high-income areas. But interestingly, by 2024, the gap between the lowest and highest income areas was essentially the same as it had been in 2019 — slightly more than 5.5 years.

California’s life expectancy deficits remained larger in Hispanic and Black populations compared to white and Asian populations: In 2024, Hispanic life expectancy was still 1.44 years below where it had been before the pandemic, for example, and Black life expectancy was 1.48 years below, whereas white and Asian populations were 0.63 of a year and 1.06 years below their prior figures, respectively.

Hispanic people have historically had longer life expectancy than white people in California, but those rankings reversed when the pandemic hit in 2020. Hispanic life expectancy recovered its advantage in 2022, but not to the degree it had held before Covid: As of 2024, Hispanic life expectancy is 1.17 years longer than white, compared with 1.98 years longer in 2019.

The study had its limitations, including the fact that the California data from 2024 is preliminary and may not be generalizable to the rest of the country. The analysis also defined income levels based on census tracts rather than individuals, which can lead to imprecision, and causes of death can be misclassified in some cases.

Dr. Schwandt emphasized that the direct causal mechanisms behind their findings were not fully understood, but certain trends stand out. The growing role of drug overdoses in the deficit from 2021 to 2023, especially in Black and low-income areas, reflects those groups’ increased exposure to fentanyl.

A sliver of good news: Drugs appeared to play a smaller role in the life expectancy deficit in 2024 than in 2023, a nod to the shrinking overdose mortality rates nationwide.