Intensity and frequency of extreme novel epidemics

Area of Science:

• Epidemiology and Biostatistics
• Global Health Security
• Historical Disease Analysis

Background:

• Understanding epidemic intensity and emergence rates is crucial for public health risk assessment and pandemic preparedness.
• A comprehensive global historical record of epidemics is needed to test theories and inform models.

Observation:

• A global dataset of historical epidemics from 1600 to the present was compiled and analyzed.
• Novel statistical methods were used to estimate the yearly probability of extreme epidemics.
• Historical epidemic data followed a generalized Pareto distribution with a power-law tail.

Findings:

• Extreme epidemics, such as the 1918 Spanish influenza, have a higher probability of occurrence than previously detected.
• The yearly probability of an event like the Spanish influenza ranges from 0.27% to 1.9%, with a current mean recurrence time of 400 years.
• The slow decay of probability with epidemic intensity indicates that extreme events are relatively likely.

Implications:

• Findings challenge previous assumptions due to short observational records and stationary analysis methods.
• Environmental change and increased zoonotic disease emergence may triple the probability of extreme epidemics in the coming decades.
• This research underscores the need for proactive global health strategies and updated pandemic risk assessments.