Mathematical modelling of infectious disease

Mathematical models can project how infectious diseases progress to show the likely outcome of an epidemic and help inform public health interventions. Models use some basic assumptions and mathematics to find parameters for various infectious diseases and use those parameters to calculate the effects of possible interventions, like mass vaccination programmes.

In epidemiology, the most fundamental property of a disease is its basic reproductive number R0, or the average number of new infections started by the first infection in a population.  When an infection first enters the population, its spread is like a chain reaction:  1 infection becomes R0 new infections, those each start new infections to make R02, then those become R04, and so on.  If R0 >1, the disease spreads in what is called an epidemic, and the larger the value of R0, the faster the spread. 

Basic reproduction number