Lost Lessons of the 1918 Influenza: The 1920s Working Hypothesis, the Public Health Paradigm, and the Prevention of Deadly Pandemics

Abstract

In standard historical accounts, the hyperlethal 1918 flu pandemic was inevitable once a novel influenza virus appeared. However, in the years following the pandemic, it was obvious to distinguished flu experts from around the world that social and environmental conditions interacted with infectious agents and could enhance the virulence of flu germs. On the basis of the timing and geographic pattern of the pandemic, they hypothesized that an "essential cause" of the pandemic's extraordinary lethality was the extreme, prolonged, and industrial-scale overcrowding of US soldiers in World War I, particularly on troopships. This literature synthesis considers research from history, public health, military medicine, veterinary science, molecular genetics, virology, immunology, and epidemiology. Arguments against the hypothesis do not provide disconfirming evidence. Overall, the findings are consistent with an immunologically similar virus varying in virulence in response to war-related conditions. The enhancement-of-virulence hypothesis deserves to be included in the history of the pandemic and the war. These lost lessons of 1918 point to possibilities for blocking the transformation of innocuous infections into deadly disasters and are relevant beyond influenza for diseases like COVID-19. (Am J Public Health. 2022;112(10):1454-1464. https://doi.org/10.2105/AJPH.2022.306976).

FIGURE 1—

Notable Influenza Experts (a) William Gorgas, (b) Major Greenwood, (c) Edwin Oakes Jordan, and (d) Frank Macfarlane Burnet Note. William Gorgas (1854–1920) was an international celebrity for his leadership of the Panama Canal Zone Sanitation Commission, and during World War I was US Army surgeon general. Major Greenwood (1880–1949) was a leading medical statistician of the first half of the 20th century and coauthored the 1920 British Ministry of Health’s report on the epidemiology of the pandemic. Edwin Oakes Jordan (1866–1936) was founding editor of the Journal of Infectious Diseases as well as the Journal of Preventive Medicine and received the Sedgwick Memorial Medal from the American Public Health Association. Frank Macfarlane Burnet (1899–1985) was an Australian virologist who won the Nobel Prize for his research in immunology. His work with influenza virus led to the methods used for many decades to manufacture influenza vaccines, and his team was the first to describe how reassortments of influenza genes could lead to the antigenic shifts that produce novel pandemic viruses. Sources. William C. Gorgas at time of Panama Canal construction: courtesy of National Library of Medicine, (NLM#101416944, Image B013225). Portrait of Major Greenwood: photograph by Walter Stoneman, UK National Portrait Gallery (NPG #67957). Portrait of E. O. Jordan: photograph by Walinger, US National Library of Medicine (#101419931, Image B015878). Portrait of Sir Frank Macfarlane Burnet: photograph by N. Murray, Wikimedia Commons (#4746503).

FIGURE 2—

Industrial-Scale, Prolonged Extreme Overcrowding on US Troopships Note. The USS Leviathan was the largest ship in the world, transporting as many as 14 000 soldiers to France at a time, versus the 4000 passengers it was designed to carry as a German ocean liner. Men slept in berths stacked four high, sometimes sharing beds in shifts. Portholes were kept closed and covered to evade submarine attacks. The voyage typically took 10 days. The return trips for demobilized troops were somewhat better, with only 8000 troops. Source. Troops seek fresh air aboard the troopship USS Leviathan: photographed by Zimmer, US Naval History and Heritage Command (Image NH 41881).

FIGURE 3—

Spread of the Severe Flu Beyond the US Army, and After 1918 Note. The war put people from around the world in contact with each other, creating opportunities for widespread transmission of infections. These contacts continued even after the Armistice, for example in prisoner of war (POW) camps, where severe flu was observed in 1919. The “Third Wave” of the pandemic corresponds with the return home of POWs, demobilized troops, and wartime guest-workers. Source. “A group of captured soldiers representing 8 nationalities: Anamite [Vietnamese], Tunese [Tunisian], Senegalese, Sudanese, Russian, American, Portugese [sic] and English.” Official German photograph from Western Front, US National Archives (Image #17391518).

FIGURE 4—

The 1920s Working Hypothesis: Enhancement of Virulence Note. War-related conditions, particularly the transoceanic transport of millions of troops on extremely overcrowded ships, constituted “experimentation” in “enhancement of virulence” of a respiratory virus. Once severe influenza appeared, it would have been dangerous for those directly exposed. A similar phenomenon is observed today with avian influenza, which can become highly virulent inside industrial poultry farms. One hypothesis for the genesis of the recent COVID-19 pandemic is that industrial wildlife-farming enhanced virulence of SARS-CoV-2. (The diagram is a conceptual description of a model and is not meant to be a precise representation of the proportion of virulent viral variants.) Source. Photograph of USS Leviathan by Kadel and Herbert, US National Archives (ID #26433439, Image #165-WW-138A-33).