Effectiveness of a Combined Vi Vaccination and Health Education Program on Reducing the Burden of Typhoid During Childhood: A Demonstration Project in Karachi

Typhoid fever is a major cause of morbidity worldwide. The disease predominantly affects school-aged children, is more prevalent in urban areas, may last for several weeks and can lead to serious complications. Management of this disease is further complicated by the emergence of multi-drug resistant strains. Vaccination of high risk populations is considered the most promising strategy for the control of typhoid fever. The Vi polysaccharide vaccine has been targeted for accelerated introduction into public health programs due to the following reasons: it has been shown to have consistent efficacy results even in areas of high typhoid incidence; is given as a single dose; lacks patent protection and requires less strict cold chain requirements. A cluster-randomized trial involving the Vi polysaccharide vaccine and an active control (hepatitis A) was designed to determine the effectiveness and the feasibility of providing Vi vaccine under actual programmatic conditions in 3 urban slums in Pakistan. The vaccines used in this study are internationally produced and locally licensed. A complimentary, targeted, basic typhoid prevention health education program for the entire population at the initiation of the project will be provided and the actual Vi-demonstration project will be preceded by a 12-month typhoid surveillance activity.

Secondary objectives of this trial are:

• To monitor the adverse events following a routine Vi mass vaccination campaign;
• To assess the knowledge, attitudes, beliefs and practices among parents and health care providers regarding typhoid illness, treatment and prevention; and
• To study typhoid fever risk factors in the population.

A nested, prospective matched case-control study is included in the trial in order to study typhoid risk factors among children in Karachi.