Review of the Disease Burden of Haemophilus Influenzae Type B (Hib), and the Use and Cost-effectiveness of Hib Vaccination in the Western Pacific Region
This study aims to critically review and analyse the disease burden due to Haemophilus influenzae type b (Hib), based on existing studies. It also reviews studies on the impact of the Hib vaccine on child morbidity and mortality, and on the cost-effectiveness of mass vaccination of the eligible population in the Western Pacific Region. In addition, it examines current vaccination policies in the Western Pacific Region for Hib, including the types of vaccines used and vaccination schedules.Methods used for the review include: (1) review of all published and accessible unpublished literature on Hib, including communications from experts; and (2) comparison of economic evaluation studies across regions and a sensitivity analysis for different disease burden scenarios.Review of existing studies reveals significant variation in disease burden due to Hib among subregions and countries in the Western Pacific Region. Acknowledging the limited number of studies and their methodological limitations, the incidence of Hib meningitis in the East Asia subregion, comprising 13 countries and areas, is estimated to be lower than 40 per 100 000 under-5 population, except in the Philippines. In the Oceania subregion, comprising 24 countries and areas, Australia, French Polynesia and New Zealand show similar rates of Hib meningitis incidence, at about 30 per 100 000 under-5 population. Data generated from a rapid assessment tool (RAT) in the Pacific island countries and areas suggests a higher incidence, from 50 to 84 per 100 000 under-5 population. Regarding Hib vaccination, 23 out of 37 countries and areas in the Western Pacific Region have introduced the vaccine and 18 countries have incorporated it into their routine immunization programmes, with two more countries planning to do so in 2007. Three countries (Australia, Fiji and New Zealand) with data on the impact of Hib vaccination have reported a dramatic decrease in Hib incidence following introduction of the vaccination. The cost–benefit ratio of universal Hib immunization in the Western Pacific Region seems to be lower than observed in the WHO Region of the Americas or the WHO European Region, mainly because of relatively lower incidence.Seventeen countries and areas have no data on Hib disease burden, though some have introduced Hib vaccination (e.g. Brunei Darussalam). Many of the available disease burden data in the Region are based on hospital-based or retrospective studies, with only seven out of 40 studies on Hib disease burden being community-based prospective studies. In order to decide whether or not to introduce Hib vaccination, and to evaluate the economic value or impact of immunization, well-designed studies using innovative methodologies should be carried out to assess the Hib disease burden and the cost-effectiveness of vaccination with minimum resources and time.