Related Experiment Videos
Observations on mortality during the 1918 influenza pandemic
1Department of Internal Medicine, Hackensack University Medical Center, Hackensack, New Jersey 07601, USA.
Summary
The 1918 influenza pandemic showed unexpected mortality patterns, not the typical W-shape. Elderly individuals experienced lower mortality, suggesting prior immunity to the H1N1 strain.
Area of Science:
- Epidemiology
- Virology
- Public Health
Background:
- The 1918 influenza pandemic is known for its unusual W-shaped mortality curve.
- This curve typically shows peaks in mortality among the very young, the elderly, and young adults (20-40 years).
Purpose of the Study:
- To investigate the W-shaped mortality curve of the 1918 influenza pandemic.
- To explain the observed peak mortality in young adults aged 20-40 years.
- To compare the 1918 pandemic's mortality patterns with those of the 1957 and 1968 influenza pandemics.
Main Methods:
- Age-specific excess mortality was calculated for the 1918 pandemic using a 5-year baseline.
- Excess mortality curves for the 1957 and 1968 pandemics were also generated using 5-year baselines for comparison.
Main Results:
- The 1957 and 1968 pandemic curves showed a typical U-shape, with higher excess mortality in infants and the elderly.
- The 1918 pandemic curve did not exhibit the expected W-shape.
- A peak in excess mortality was observed in infants and young adults, but not the elderly.
Conclusions:
- The 1918 pandemic's mortality curve differed significantly from the U-shaped curves of later pandemics.
- Negative excess mortality in the elderly suggests they may have had pre-existing immunity.
- This immunity could be due to prior exposure to an influenza A (H1N1) strain similar to the one causing the 1918 pandemic.