What Can We Learn from the Spanish Flu Pandemic of 1918-19 for COVID-19?

Abstract

T he COVID-19 pandemic has spurred intense efforts among researchers to estimate the likely course of the pandemic and its economic effects. Several studies have sought insights from global pandemics of the past, including the Spanish flu pandemic of 1918-19, which is thought to have infected some 500 million persons, or about one-third of the world's population, and killed anywhere from 50 to 100 million people. 1 Lessons from the Spanish flu pandemic are relevant and informative. Like COVID-19, the Spanish flu was highly contagious; it was also unusually lethal compared with a typical seasonal flu. As the flu became more widespread and its dangers apparent, many cities sought to contain the virus by imposing restrictions on social and economic interactions. These efforts can provide insights about the economic and public health impacts of government efforts to limit the spread of pandemic diseases. This essay discusses some recent research findings on the effects of the Spanish flu pandemic and measures that cities took to control it. The Spanish flu pandemic came in three waves beginning in the spring of 1918. The second wave, in the fall of 1918, was the largest by far in terms of total infections and deaths. A third wave occurred in the spring of 1919. Overall, the pandemic is estimated to have infected about 25 percent of the U.S. population, or about 25 million people, and killed 675,000 for roughly a 3 percent mortality rate. 2 The pandemic began during World War I, and the virus is thought to have been introduced and spread throughout the United States by soldiers returning from Europe. By the end of 1918, some 45,000 U.S. soldiers had contracted and died from the disease, a number only modestly smaller than the 53,000 American combat deaths. 3 As with typical seasonal flu, young children and the elderly were particularly susceptible to the Spanish flu. However, the Spanish flu was especially lethal for young, "prime-age" adults, especially men. In 1918, the mortality rate from the flu and pneumonia among men 15 to 34 years of age was more than 20 times higher than in previous years, and throughout the pandemic, half of all flu deaths were among adults between 20 and 40 years of age. Furthermore, the absolute