Chapter 4

What do models tell us about the dynamics of infections?

This chapter discusses the insights that models provide into the dynamics of acute infections and the impact of control. It begins by considering the short-term dynamics, discussing why epidemics occur, how data from the early stages of an epidemic can be analysed to infer the basic reproduction number and the future number of cases, and the level of control required to control an infection.

It then focuses on the long-term dynamics of infections, discussing why cycles in immunizing infections occur, and contrasts these against the patterns seen for non-immunizing infections. Examples of diseases that are discussed in this chapter include influenza, measles, rubella, syphilis, and pertussis.

Quarterly notification rates of measles and measles vaccination coverage in England and Wales (data sources: Health Protection Agency and Office for Population Censuses and Surveys)

Before the introduction of vaccination, measles epidemics occurred roughly every two years in England and Wales; the introduction of measles vaccination in 1968 had a dramatic effect on these epidemics.

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