By how much did life expectancy fall because of the COVID-19 pandemic? A new study suggests that pandemics require a new method to accurately calculate life expectancy: “hybrid life expectancy” takes the duration of the pandemic into account, revealing that health crises have much smaller impact on life expectancy than previous studies have suggested.

The coronavirus pandemic caused over one million deaths in the United States from 2021 to 2023. According to the Human Mortality Database, the world’s leading scientific data resource on mortality in more developed countries, life expectancy at birth in the United States fell from 78.99 years in 2019 to 76.43 years in 2021. This significant decline has been widely discussed in the media. A press release from the Centers for Disease Control and Prevention’s (CDC) National Center for Health Statistics states that the life expectancy decline from 2019 to 2021 “was the biggest two-year decline in life expectancy since 1921-1923”. Statements like this influence policymakers’ understanding of the severity of the COVID-19 pandemic and impact how people perceive and react to pandemic-related policies.

To assess the magnitude of the COVID-19 pandemic in the United States, a common approach was to calculate the differences in life expectancy at birth during a pandemic year (i.e., 2021), and the year before the pandemic (2019). Such comparisons are misleading as they do not account for the duration of the pandemic. The calculation of life expectancy in 2019 assumes that people spend their entire lives experiencing pre-pandemic mortality rates, while the calculation of life expectancy in 2021 assumes that people live their entire lives in a permanent pandemic. However, people do not live their entire lives experiencing the mortality rates of 2021.

A new IIASA study published in Biology Methods and Protocols introduces a novel method for calculating life expectancy that reflects the experience of people enduring pandemic-level mortality rates for fixed durations.

“We call it hybrid life expectancy because it integrates both pandemic and pre-pandemic mortality rates,” explains Sergei Scherbov, study coauthor and IIASA Distinguished Emeritus Research Scholar in the IIASA Population and Just Societies Program.

The results show that the difference in life expectancy at birth in the United States in 2019 with and without a three-year-long pandemic is 0.01 years (approximately 3.65 days). Pandemics did not impact mortality rates at younger ages, so a three-year-long pandemic has no effect on life expectancy at birth.  Incorporating a three-year-long pandemic into life expectancy at age 65 results in a decrease of 0.18 years, which is roughly equivalent to 66 days compared to what life expectancy would have been without it.

“When we consider the length of the COVID-19 pandemic, the decrease in life expectancy is much smaller using the hybrid life expectancy method, compared to not taking the pandemic’s duration into account,” says Warren Sanderson, study coauthor and IIASA guest researcher in the IIASA Population and Just Societies Program. “People were misinformed about the effects of the COVID-19 pandemic on life expectancy. Media discussions about life expectancy were greatly exaggerated because they assumed the pandemic would last for people’s entire lifetime.”

The study recommends that life expectancy reductions calculated in the traditional way should not be used to assess the magnitude of pandemics. Instead, it advocates utilizing the hybrid life expectancy method for a more accurate assessment.


Sanderson, W., Scherbov, S. (2023). The Effect of the COVID-19 Pandemic on Life Expectancy in the US: An Application of Hybrid Life Expectancy. Biology Methods and Protocols


African school girl posing at a school desk with pen and paper

04 December 2023

Filling data gaps to assess the role of education in fertility decline

IIASA researchers have introduced an innovative methodology for reconstructing data on fertility and education, particularly in developing countries with inconsistent or unreliable data sets.
beautiful autumn panorama of the Carpathians Ukraine-lake, forest.

29 November 2023

Setting out priority areas of cooperation and concrete action for Ukraine’s forests

Modern, target-oriented research and quality education, more exchange with international peers and partners, better science-policy interaction, and improved coordination and communication with international and national actors are crucial for ensuring a sustainable future of Ukraine’s forests.
AI generated image in the shape of a water drop - concept of scarce resources

28 November 2023

How can we evaluate the quality of global water models?

IIASA researchers contributed to a new international study that tested the extent to which global water models agree with each other and with observational data. Using a new evaluation approach, the researchers can show in which climate regions the models agree and where they differ.