Seasonal infectious disease epidemiology

TLDR

Seasonal incidence of infectious diseases is common worldwide, yet the mechanisms driving this pattern and its epidemiological implications remain poorly understood, and standard concepts such as R₀ and periodic interventions like pulse vaccination have not been formally examined. This paper investigates the causes and consequences of seasonality, deriving new insights into vaccination strategy and the interpretation of outbreak data. It reviews published evidence to identify four principal mechanisms linked to transmission routes, discusses their effects on R₀, outbreaks, endemic dynamics, and persistence, and presents a mathematical analysis of routine and pulse vaccination programmes for seasonal infections. The synthesis underscores the need for further empirical and theoretical research in seasonal infectious disease epidemiology.

Abstract

Seasonal change in the incidence of infectious diseases is a common phenomenon in both temperate and tropical climates. However, the mechanisms responsible for seasonal disease incidence, and the epidemiological consequences of seasonality, are poorly understood with rare exception. Standard epidemiological theory and concepts such as the basic reproductive number R 0 no longer apply, and the implications for interventions that themselves may be periodic, such as pulse vaccination, have not been formally examined. This paper examines the causes and consequences of seasonality, and in so doing derives several new results concerning vaccination strategy and the interpretation of disease outbreak data. It begins with a brief review of published scientific studies in support of different causes of seasonality in infectious diseases of humans, identifying four principal mechanisms and their association with different routes of transmission. It then describes the consequences of seasonality for R 0 , disease outbreaks, endemic dynamics and persistence. Finally, a mathematical analysis of routine and pulse vaccination programmes for seasonal infections is presented. The synthesis of seasonal infectious disease epidemiology attempted by this paper highlights the need for further empirical and theoretical work.