Epidemiology is the study of the distribution, dynamics, and determinants of diseases in populations.

Epidemiology includes:

  • Mechanisms of viral transmission
  • Risk factors for infection,
  • Population size required for virus transmission
  • Geography
  • Season
  • Means of control

The risk of virus infection and/or disease in a human population is determined by the characteristics both of the virus, of susceptible individuals and of the host population such as innate and acquired resistance. In addition, virus transmission is affected by behavioural, environmental, and ecological factors.

Epidemiology can also help to clarify the role of viruses in the aetiology of diseases, understand the interaction of viruses with environmental determinants of disease, determine factors affecting host susceptibility, clarify modes of transmission, and the testing of vaccines and therapeutics on a large scale.