Introduction of Hib conjugate vaccines in the non-industrialized world: experience in four ‘newly adopting’ countries
Introduction
The relatively stable picture of routine national immunization priorities is now changing. For the last 30 years, national immunization programs in most countries have focused on providing children with the six original antigens recommended for routine infant use by WHO's Expanded Programme on Immunization (EPI) — diphtheria, pertussis, tetanus, polio, measles and BCG. In areas where yellow fever is endemic, yellow fever vaccine is also recommended. In 1990, the World Health Assembly recommended hepatitis b vaccine for universal infant immunization, and efforts to introduce this vaccine are continuing. Progress in research on new vaccines for several infectious diseases of world-wide importance is now resulting in an unprecedented number of new immunization options. Haemophilus influenzae type b (Hib) conjugate vaccines are already used in routine infant immunization programs in over 30 countries, and new vaccines for infections caused by Streptococcus pneumoniae and rotavirus — major causes of childhood morbidity and mortality world-wide — will probably be licensed in the next 5 yr. How countries and national immunization programs deal with these new prevention opportunities will be a critical issue in the next decade. WHO has published a framework for evaluating new vaccines for integration into national immunization programs [1] and there has been increasing interest in factors that lead to adoption of new vaccines into national programs [2], [3], but there are as yet little data on this topic from the developing world.
Hib vaccines are the first in the new crop of vaccines with potentially world-wide utility. The most obvious manifestation of Hib disease is childhood meningitis, and in most countries in which it has been studied, Hib is the major cause of bacterial meningitis in children less than 5 yr of age. More importantly, in developing countries, where acute respiratory infection is the most common single cause of infant mortality, Hib is the second most common cause of bacterial pneumonia deaths. The Hib conjugate vaccines are safe, and greater than 90% effective against both meningitis and pneumonia due to Hib [4], [5], [6], [7]. They are available in liquid or lyophilized forms, and can be administered separately or in some cases in the same syringe with DTP. The recommended infant immunization schedules are the same as for DTP, so no additional visits must be added to routine immunization schedules. The attractiveness of the potential impact of Hib conjugate vaccines on disease, and compatibility of these vaccines with current immunization schedules noted above is moderated by their current pricing (recently between 2 and 4.5 US$ per dose), which is high relative to other antigens used routinely in national immunization programs in developing countries.
WHO has recently recommended inclusion of Hib conjugate vaccines in routine infant immunization programmes as appropriate to national capacities and priorities [8]. In spite of the potentially large number of national Hib vaccine introductions looming in the future, little is known about (1) the process involved in deciding to introduce Hib vaccines into a national program; (2) the most useful mode of introduction (especially in terms of product formulation and combinations); and (3) the potential impact of Hib vaccine introduction on national immunization programs. We evaluated four countries in two regions which recently introduced Hib vaccines as a routine infant immunization, two in Latin America (Uruguay and Chile, with national introductions in 1994 and 1996 respectively) and two in WHO's Eastern Mediterranean region (Qatar and Kuwait, national introductions 1993 and 1997). Through site visits and use of a standardized questionnaire we performed an evaluation of the introduction of Hib conjugate vaccines. In addition to providing some insight into the decision-making process, our data illustrates the impact and challenges presented by new vaccine introduction, information which will be helpful for other countries in the process of evaluating or introducing new vaccines.
Section snippets
Methods
Table 1 shows population characteristics and proportion of children receiving the primary series of DTP vaccine by 1 yr of age in the four countries evaluated.
A data collection form was prepared to elicit information in four areas — decision-making, mode of introduction, immunogenicity and effectiveness, and impact on the national immunization program. The process used to reach the decision to introduce Hib vaccine was addressed by requesting information including who was involved in the
Decision-making
All respondents stated that the initiator for the decision-making process was the Ministry of Health (various combinations of the epidemiology and/or immunization groups) with the major support for introduction coming from national pediatrician groups and individual pediatric opinion leaders. All respondents noted that an appreciation of the burden of Hib disease was a key factor in making a decision to adopt the vaccine. Studies on Hib disease burden performed in three of the four countries
Discussion
We evaluated the experience of four countries, which were the first in their respective regions to introduce the Hib conjugate vaccines as a routine infant immunization. Although these evaluations were done relatively soon after introduction, and subsequent experience will be critical in assessing issues such as impact on disease and immunization programs, including coverage and wastage, our observations allow some inferences to be drawn about introduction, and can provide some guidance to
Acknowledgements
The authors wish to thank the following national public health personnel for facilitating this effort and for providing information on experience with Hib vaccine introduction – Dr. Irene Leal Sanchez, EPI, Ministry of Health, Chile; Dr. Mussab I. Al-Saleh, Head EPI and Infectious Disease Control, Ministry of Health, Kuwait; Dr. Khalifa A. Al Jaber, Director of Preventive Medicine, Ministry of Public Health, Qatar; and Dr. Gloria Ruocco, EPI, Ministry of Health, Uruguay.
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Haemophilus influenzae type b conjugate vaccines - A South African perspective
2012, VaccineCitation Excerpt :Invasive disease represented only part of the clinical implication, as meningitis is often complicated with hearing impairment, seizure disorders, cognitive and developmental delay, and various other permanent neurological sequelae [8]. Introduction of Hib vaccination has had a major impact on invasive disease in both developing [9–12] and industrialized countries [7,13,14] despite the fact that disease epidemiology differs in these settings (Table 1). South Africa was the first African country to introduce Hib vaccine as part of the National Expanded Program on Immunization (EPI) in 1999 [15]; the estimated coverage in 2004 was 92% [6].
Impact of vaccination against Haemophilus influenzae type b with and without a booster dose on meningitis in four South American countries
2012, VaccineCitation Excerpt :Schedules in Uruguay recommended a booster at 12 months and in Argentina at 18 months; Chile and Colombia did not recommend a booster [8]. Hib conjugate vaccines were available in the private sector in all four countries prior to their introduction in the national immunization program, although private purchase accounted for a small number of doses [8,11,12]. All four countries have national, laboratory-based surveillance for invasive bacterial diseases.