Estimation of the direct and indirect effects of vaccination

Stat Med. 1999 Aug 30;18(16):2101-9. doi: 10.1002/(sici)1097-0258(19990830)18:16<2101::aid-sim178>;2-6.


Indirect effects play a major role in the protection afforded by a vaccination programme. In this work we define new measures of direct, indirect and total (direct + indirect) effects of a vaccination programme in terms of the protection they provide to unvaccinated and vaccinated individuals, and to the entire population. We show how these measures can be estimated using data from a vaccine trial or an observational study. The bias and standard errors of these estimates can be evaluated via stochastic simulations. Examples from a mumps outbreak and a (hypothetical) HIV vaccine trial are used to illustrate the estimation of these new measures of vaccination effectiveness.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • AIDS Vaccines / administration & dosage
  • Bias
  • Child
  • Disease Outbreaks / prevention & control
  • Female
  • HIV Infections / prevention & control
  • HIV Infections / transmission
  • Humans
  • Male
  • Models, Statistical*
  • Mumps / prevention & control
  • Mumps Vaccine / administration & dosage
  • Probability
  • Random Allocation
  • Stochastic Processes*
  • Vaccination*


  • AIDS Vaccines
  • Mumps Vaccine