Despite the availability of at least two licensed typhoid fever
vaccines-injectable sub-unit Vi polysaccharide vaccine and live, oral
Ty21a vaccine-for the last decade, these vaccines have not been widely
introduced in public-health programmes in countries endemic for typhoid
fever. The goal of the multidisciplinary DOMI (Diseases of the Most
Impoverished) typhoid fever programme is to generate policy-relevant
data to support public decision-making regarding the introduction of Vi
polysaccharide typhoid fever immunization programmes in China, Viet
Nam, Pakistan, India, Bangladesh, and Indonesia. Through
epidemiological studies, the DOMI Programme is generating these data
and is offering a model for the accelerated, rational introduction of
new vaccines into health programmes in low-income countries. Practical
and specific examples of the role of epidemiology are described in this
paper. These examples cover: (a) selection of available typhoid fever
vaccines to be introduced in the programme, (b) generation of
policy-relevant data, (c) providing the 'backbone' for the
implementation of other multidisciplinary projects, and (d) generation
of unexpected but useful information relevant for the introduction of
vaccines. Epidemiological studies contribute to all stages of
development of vaccine evaluation and introduction