U.S. life expectancy dropped for the second consecutive year in 2021, falling by nearly a year from 2020, according to a report by the Centers for Disease Control and Prevention.

In the first two years of the COVID-19 pandemic, the estimated American lifespan has shortened by nearly three years. The last comparable decrease happened in the early 1940s, during the height of World War II.

Centers for Disease Control and Prevention officials blamed COVID-19 for about half the decline in 2021, a year when vaccinations became widely available but new coronavirus variants caused waves of hospitalizations and deaths. Other contributors to the decline are longstanding problems: drug overdoses, heart disease, suicide, and chronic liver disease. “It’s a dismal situation. It was bad before and it’s gotten worse,” Samuel Preston, a University of Pennsylvania demographer, told the Associated Press, which reported extensively on the CDC report.

Life expectancy is an estimate of the average number of years a baby born in a given year might expect to live, given death rates at that time. It is “the most fundamental indicator of population health in this country,” said Robert Hummer, a University of North Carolina researcher focused on population health patterns.

U.S. life expectancy rose for decades, but progress stalled before the pandemic. It was 78 years, 10 months in 2019. In 2020, it dropped to 77 years. Last year, it fell to about 76 years, 1 month.

The last time it was that low was in 1996.

Oneida County Health Director Daniel Gilmore said that while life expectancy data is not maintained by the county, it’s likely that the county is following regional and national trends. Oneida County has seen an increase in both drug overdoses and overdose fatalities during the pandemic, and there have been approximately 700 locally reported COVID deaths in the county, he said.

Another factor to note, “During the pandemic, many individuals did not obtain their scheduled visits with primary health care providers, health care specialists, and dentists,” Gilmore added.

Declines during the pandemic were worse for some racial groups, and some gaps widened. For example, life expectancy for American Indian and Alaskan Native people saw a decline of more than 6 1/2 years since the pandemic began, and is at 65 years.

Experts say there are many possible reasons for such differences, including lack of access to quality health care, lower vaccination rates, and a greater share of the population in lower-paying jobs that required them to keep working when the pandemic was at its worst.

The new report is based on provisional data. Life expectancy estimates can change with the addition of more data and further analysis. But it’s likely the declines in 2020 and 2021 will stand as the first two consecutive years of declining life expectancy in the U.S. since the early 1960s, CDC officials said.

COVID-19 deaths were the main reason for the decline. The second largest contributor was deaths from accidental injuries — primarily from drug overdoses, which killed a record-breaking 107,000 Americans last year.

The report also suggests gains against suicide are being undone, according to the AP.

U.S. suicides rose from the early 2000s until 2018 and reportedly fell slightly in 2019 and then more in 2020, the first year of the pandemic. Experts had wondered if that may have been related to a phenomenon seen in the early stages of wars and national disasters in which people band together and support each other.

The new report said suicide contributed to the decline in life expectancy in 2021, but it did not provide detail. According to provisional numbers from a public CDC database, the number of U.S. suicides increased last year by about 2,000, to 48,000. The U.S. suicide rate rose as well, from 13.5 per 100,000 to 14.1 — bringing it back up to about where it was in 2018.

The Associated Press contributed to this story.