Elsevier

The Lancet

Volume 348, Issue 9033, 12 October 1996, Pages 1010-1013
The Lancet

Series
Low-efficacy HIV vaccines: potential for community-based intervention programmes

https://doi.org/10.1016/S0140-6736(96)07100-0Get rights and content

Summary

To combat the spread of HIV, progress on vaccine development is eagerly awaited. Haynes in this series has described the progress made so far with various vaccine types. This article describes how mathematical modelling techniques can be used to predict the likely impact of low-efficacy vaccines in community transmission of the virus. The answers are often not what one would predict by intuition alone, and they have great bearing on the likely success of such vaccination strategies.

Section snippets

Vaccination and the individual

Parameters for evaluating vaccine efficacy must be defined precisely to facilitate measurement and evaluation in phase III trials.8, 9, 10 Mathematical representation of the effect of vaccination on the individual helps in this process. The parameters shown in the panel are central to that analysis.

We therefore arrive at a minimum of eight parameters that must be measured to assess the impact of vaccination on the individual. Recent work on the measurement of impact by McLean and Blower11 made

Vaccination and the community

The manner in which different properties of the vaccine act to reduce the rate of spread of HIV-1 in a vaccinated population is most easily understood by reference to their impact on the basic reproductive number of infection, Ro, which defines the average number of secondary cases of infection generated by one primary case in a susceptible population.12 The magnitude of Ro is determined by parameters that describe the typical course of infection in an individual and those that determine

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