An exploratory method for estimating the changing speed of epidemic waves from historical data

Area of Science:

• Epidemiology
• Public Health
• Statistical Modeling

Background:

• Accurate historical disease data is crucial for understanding long-term incidence trends.
• Historical data often presents challenges due to unspecified accuracy and reliability.
• Analyzing spatio-temporal disease dynamics requires robust methodologies.

Purpose of the Study:

• To propose a robust measure for the spatial velocity of epidemic waves using binary data.
• To apply this novel measure to historical influenza morbidity records in Iceland.
• To analyze long-term trends in influenza epidemic spread and timing.

Main Methods:

• Development of a spatial velocity measure, R(0A), for epidemic waves.
• Application of R(0A) to 61 years of Icelandic influenza season data (1915-1976).
• Analysis of spatio-temporal patterns and wave characteristics.

Main Results:

• Influenza wave onset showed an accelerating trend over the study period.
• Pandemic waves (H1N1, H2N2, H3N2) spread significantly faster and occurred earlier than inter-pandemic waves.
• Wave velocity analysis revealed distinct patterns for pandemic versus inter-pandemic influenza seasons.

Conclusions:

• The R(0A) measure is applicable to historical time-series data with regional breakdowns.
• The study explored the real-time application of R(0A) using French influenza data.
• Further research will extend the analysis to other countries and diseases.