The 1918-1920 influenza pandemic in Peru

Area of Science:

• Epidemiology
• Historical Public Health
• Virology

Background:

• Understanding past influenza pandemic patterns is vital for future preparedness.
• Archival research in Peru characterized the 1918-1920 influenza pandemic's temporal, age, and geographic dynamics.

Purpose of the Study:

• To analyze the temporal, age, and geographic patterns of the 1918-1920 influenza pandemic in Peru.
• To guide future influenza pandemic preparedness plans through regional analysis.

Main Methods:

• Quantitative analysis of 52,739 individual mortality records from Peruvian archives (Lima, Iquitos, Ica).
• Application of seasonal excess mortality models to respiratory mortality rates (1917-1920).
• Estimation of transmissibility using daily growth rates in respiratory deaths.

Main Results:

• A synchronized severe pandemic wave occurred from November 1918 to February 1919 across all three cities.
• Asynchronous recrudescent waves were observed in 1920, particularly impacting Lima.
• Iquitos had higher cumulative excess mortality (2.9%) than Lima (1.6%); Lima's mean reproduction number was 1.3-1.5.

Conclusions:

• The 1918 influenza pandemic in Peru featured synchronized and asynchronous waves with significant excess mortality.
• Middle-aged groups experienced the highest relative excess mortality.
• Further studies in under-researched regions are needed to grasp the global impact of the 1918 influenza virus.