A Centenary Tale of Two Pandemics: The 1918 Influenza Pandemic and COVID-19, Part I

Abstract

Separated by a century, the influenza pandemic of 1918 and the COVID-19 pandemic of 2019-2021 are among the most disastrous infectious disease emergences of modern times. Although caused by unrelated viruses, the two pandemics are nevertheless similar in their clinical, pathological, and epidemiological features, and in the civic, public health, and medical responses to combat them. Comparing and contrasting the two pandemics, we consider what lessons we have learned over the span of a century and how we are applying those lessons to the challenges of COVID-19.

FIGURE 1—

Both the (a) 1918 and the (b) 2020 Pandemics Featured Hastily Assembled Cemeteries, Mass Graves, and Collections of Unburied Bodies Note. Photo by Willy Kurniawan, courtesy of Reuters. Printed with permission.

FIGURE 2—

Comparing Pandemics: 1918 Influenza and 2019 COVID-19 Note. DAD = diffuse alveolar damage; ICU = intensive care unit; SARS-CoV-2 = severe acute respiratory syndrome-2.

FIGURE 3—

Representative Pulmonary Histopathology of (a) Fatal 1918 Influenza and (b) Fatal SARS-CoV-2 Infection Showing Acute Diffuse Alveolar Damage With Pulmonary Edema and Hyaline Membranes Source. Sauter et al. and Sheng et al. Note. SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2. The histologic patterns of acute diffuse alveolar damage are virtually indistinguishable.

FIGURE 4—

Age-Specific Morbidity and Mortality of Influenza in 1918–1919 and, for Comparison, in 1928–1929, as Determined by US “P and I” Data by (a) Incidence per 100 Persons Ill With Pneumonia and Influenza per Age Group; (b) Mortality per 1000 Persons per Age Group; and (c) Case‒Fatality Source. Morens and Taubenberger. Note. P and I = pneumonia and influenza. Parts b and c compare the W-shaped curves of age-specific mortality and case‒fatality seen in 1918–1919 with more typical U-shaped curves from 1928 to 1929. Between 1889 and the present time, U-shaped curves have been seen in all pandemics and seasonal epidemics except for 1918 and the several years thereafter. Morbidity and mortality data reflecting diagnoses of pneumonia and influenza (so-called “P and I”) are still widely used today for epidemiological purposes (e.g., for estimating total influenza deaths during periods of influenza prevalence) because incomplete morbidity reporting and imperfect death certificate accuracy greatly underestimate infections and deaths from influenza and its secondary bacterial complications. National or large-population data permitting similar calculations for COVID-19 are not yet available, although preliminary data suggest that age-specific mortality is very low in infants and children, rising regularly with age thereafter.