Table 1.
Context and impacts of major pandemics.
| Black Death 1347–1351 | Smallpox (New World) 1520–1527 | Spanish Flu 1918–1920 | COVID-19 2020* | |
|---|---|---|---|---|
| World Population (1) | 364.8 million | 450.8 million (Americas 60.5 million) (2) | 1.86 billion | 7.80 billion |
| Mortality (% global population) | In Europe, ≥25 million (25–75% of European population) (3) | 2–15 million Aztec deaths (4) 200,000 Incan deaths Major contributor to 90% population decline in the Americans from 1,500 to 1,600 (2) |
17.4–50 million (1–3%) (5, 6) | 1,664,344 (0.02%) (7) |
| Case Fatality Rates | Bubonic plague: 50–60% Pneumonic or septicemic plague: approaching 100% (8) |
Estimated ≥50% among Aztecs and North Americans (9) | 2–3% (5) | 0.25–3.0% (10) (lower estimates more likely) |
| Number Infected | Unknown | Unknown | 500 million (clinically apparent) (5) | 75.1 million (7) |
| Notable Risk Factor(s) for Severe Disease | Overcrowding, poor housing; proximity to fleas and animal reservoir (8) | No previous exposure to disease in region (“virgin soil”) (4) | Healthy 15–40 year olds, secondary bacterial infection (5) | Old age, pre-existing conditions (11) |
| Transmission | Flea bite or close contact with respiratory droplets of a pneumonic plague patient (8) Low direct interpersonal transmission |
Contact with respiratory droplets or aerosols. Patterns of behavior (contact with the sick) likely enhanced spread (12) Low dose can be infectious (13) |
Contact with respiratory droplets or aerosols (5) | Contact with respiratory droplets or aerosols (14). |
| Available medical interventions and scientific understanding | No knowledge of germ theory; contemporary physicians admitted no known effective cures or treatments and recommended fumigation, bleeding, purging, etc. (15) | No knowledge of germ theory or effective treatment among Europeans or Americans. Among Native Americans, isolation and traditional medical practices (e.g., sweat lodges, bathing) (9) | Knowledge of germ theory but misidentification of aetioglocal agent. Palliative care and homeopathy employed. No vaccine, antiviral, ventilators, or antibiotics for secondary pneumonia (16) | Causative virus isolated and genome sequenced. Vaccines in advanced trials and roll-out, general antiviral, anti-inflammatory, and antibiotic medications available. Ventilators and modern medical practice in use (14) |
| Disease Control Strategy (at the time) | Travel restrictions and isolation at the city-state level. Usually severely enforced and aimed against specific people groups (17) First record of quarantine. |
Minimal; among Native Americans, little evidence for isolation of the sick or other nonpharmaceutical interventions (12) | Masks, social distancing, public closures, limits on public gatherings. Poorly and sporadically enforced; ineffectual and too late (17) | Near-global lockdown, quarantine, masks, track and trace (14) Implementation varies by country, ranging from highly successful to poorly enforced. |
| Population Effects | Strong, lasting effect negative effect on global population growth. European population did not recover to pre-plague levels until mid-16th century (18) | Minimal effect on global population growth, but wiped out populations in New World (~90%), extinction of some people groups (4) | Temporary global population growth decline during period of outbreak (6) | No anticipated effects on global population growth. Corollary effects on public health may reduce life expectancy (19) |
| Long Term Economic Effects | Labor shortages led to higher wages, European peasant revolts, and shifts in sociodemographic power dynamics. Increased innovation and mobility of labor (18) | Shift balance of power in New World, leading to societal collapse of Native Americans and enriching colonial European powers (4) | Limited and obscured by WWI. Sharp but short-term effects on industry. Entry of new groups into labor force (20) Towns that had quick shutdowns fared better |
Unclear; driven by large-scale response methods and spontaneous reduction of economic activity. Predicted surge in poverty, lower investment, reduced global trade. Strongest impact in developing economies (21) |
*
Figures accurate as of 18 December, 2020.