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2: Types of intervention and their development

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    • 2.1: Introduction to types of intervention and their development
      This book is about the evaluation of the effectiveness of health-related interventions. We use the term ‘intervention’ to apply to any activity undertaken with the objective of improving human health by preventing disease, by curing or reducing the severity or duration of an existing disease, or by restoring function lost through disease or injury.
    • 2.2: Types of intervention
      Interventions can be classified into two broad categories: (1) preventive interventions are those that prevent disease from occurring and thus reduce the incidence (new cases) of disease, and (2) therapeutic interventions are those that treat, mitigate, or postpone the effects of disease, once it is under way, and thus reduce the case fatality rate or reduce the disability or morbidity associated with a disease. Some interventions may have both effects.
    • 2.3: Evolution of new intervention products and sequence of study phases
      Many intervention products, and especially drugs and vaccines, are likely to originate from basic research in laboratories. Such products must go through a long series of tests, before they can be considered for use in the kinds of field trials that are the focus of this book. Before any human use, a new product will be tested in the laboratory for its activity and toxicity in various in vitro and animal test systems.
    • 2.4: References
      Brown, C. A. and Lilford, R. J. 2006. The stepped wedge trial design: a systematic review. BMC Medical Research Methodology, 6, 54. Available at: <>.