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Comparing the Influenza Pandemic of 1918 to Covid-19

The advent of the Covid-19 pandemic has renewed interest in the influenza pandemic of 1918. A new article surveyed research on the 20th-century pandemic, focusing on understanding its health and economic effects. The article identified two takeaways from the 1918 pandemic that should be considered when comparing historical pandemics to the current virus. First, health effects of that pandemic were large and diffuse, making generalizations difficult. Second, the 1918 pandemic caused the economy to contract, but scholars disagree about the size and duration. Poor-quality data and the influence of concurrent events (such as the end of World War I) further complicate the picture.

The article, by researchers at Carnegie Mellon University (CMU), Vanderbilt University, and Oberlin College, was published as a working paper with the National Bureau of Economic Research (NBER).

“The 1918 influenza pandemic is the most recent pandemic to share a number of important parallels with Covid-19,” explains Karen Clay, professor of economics and public policy at CMU’s Heinz College, who coauthored the article. “These parallels have renewed interest in understanding the health and economic effects of the 1918 pandemic as a way of inferring something about the future, but it’s important to note differences and limitations.”

Both pandemics involve novel, highly contagious, respiratory diseases that were caused by a virus; both pandemics spread across the globe in a matter of months; and both pandemics saw the adoption of nonpharmaceutical interventions like social distancing and mask wearing to slow the spread in the face of uncertainty about how to treat the illnesses medically.

In their analysis, the authors looked at the effects across the globe of the earlier pandemic on mortality, fertility, and the economy in the short and medium term. They also looked at longer-lasting health consequences and their impact on the accumulation of human capital and socioeconomic status.

In terms of health effects, the 1918 pandemic was severe, killing 50 million to 100 million people, but most who contracted the virus survived—similar to how Covid-19 has affected populations thus far. Intensity of the 20th-century pandemic varied substantially, with survivors of the initial infection facing elevated risk of mortality and some physiological conditions that never fully healed—issues that could affect those who contract Covid-19. Population density, air pollution, and nonpharmaceutical interventions played a role in determining who lived and who died from the 1918 influenza, though nonpharmaceutical interventions were less stringent than they are today.

In addition, individuals who were exposed to the 1918 pandemic in utero grew up to be in worse health and of lower socioeconomic status than those who were not exposed in this way, suggesting that the in utero effects of Covid-19 warrant attention. But unlike the 1918 pandemic, Covid-19 is less likely to kill women of childbearing age, though in both pandemics, childbearing may be delayed in response to economic and public health uncertainties.

In terms of economic effects, the 1918 pandemic caused a contraction, reducing both GDP and employment. In the 20th  century, businesses and school closed temporarily in many places, although the shutdowns were less stringent than those that took place in the spring of 2020. Studies disagree on the size and length of the economic contraction following the influenza pandemic, with researchers suggesting that it may have been driven by a negative labor supply shock because many workers of prime age died. With Covid-19, working-age adults are among the most likely to survive, so it is unlikely that today’s pandemic will generate a similarly sized negative labor supply shock.

The researchers note that the biggest challenge in estimating the effects of the 1918 pandemic was the poor-quality data and the existence of concurrent events. While they identified many important datasets, many modern datasets began shortly after the pandemic and others were collected irregularly. Moreover, the 1918 pandemic coincided with the end of World War I, which disrupted economies around the world. Both factors hinder making conclusive inferences.

“Given the substantial amount of uncertainty surrounding the Covid-19 pandemic—such as how long it will last and how many people will die from it—it is tempting to look to history for guidance,” suggests Brian Beach, assistant professor of economics at Vanderbilt University. “The 1918 pandemic offers a unique opportunity to analyze health and economic factors across a range of countries.”

But the authors caution that the two pandemics differ in important ways, including that quality of life and overall life expectancy were much lower in 1918 than they are today, and that the early 20th century economy was affected by a world war, the effect of which is difficult to disentangle from the effect of the pandemic.

The authors’ work was funded by Heinz College at CMU, Oberlin College, and Vanderbilt University.


Summarized from a working paper of the National Bureau of Economic Research (NBER), The 1989 Influenza Pandemic and Its Lessons for Covid-19 by Beach, B (Vanderbilt University), Clay, K (Carnegie Mellon University), and Saavedra, MH (Oberlin College). Copyright 2020 by the authors. All rights reserved.

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