Indian Journal of Public Health

EDITORIAL
Year
: 2012  |  Volume : 56  |  Issue : 3  |  Page : 177--179

Hib vaccine: Should it be introduced in the national immunization program?


Davendra K Taneja 
 Director-Professor, Department of Community Medicine, Maulana Azad Medical College, New Delhi, India

Correspondence Address:
Davendra K Taneja
Director-Professor, Department of Community Medicine, Maulana Azad Medical College, New Delhi
India




How to cite this article:
Taneja DK. Hib vaccine: Should it be introduced in the national immunization program?.Indian J Public Health 2012;56:177-179


How to cite this URL:
Taneja DK. Hib vaccine: Should it be introduced in the national immunization program?. Indian J Public Health [serial online] 2012 [cited 2022 Jun 30 ];56:177-179
Available from: https://www.ijph.in/text.asp?2012/56/3/177/104194


Full Text

Haemophilus influenzae type b (Hib) is estimated to cause at least 3 million cases of serious disease every year as well as approximately 386,000 deaths. Although cases occur worldwide, the burden of Hib disease is most significant in resource-poor countries. Laboratory confirmation of suspected cases of Hib infection, particularly pneumonia, is difficult to achieve, and surveillance for laboratory confirmed disease consistently underestimates the total burden of Hib disease. Laboratory diagnosis of Hib meningitis in developing countries provides underestimates due to reasons such as non performance of lumbar puncture or administration of antibiotics before admission in the hospital. Therefore, vaccine effectiveness studies provide higher estimates than based on laboratory diagnosis. [1]

The most important manifestations of Hib infection are pneumonia and meningitis. Other invasive diseases that are less frequent include septicemia, septic arthritis, osteomyelitis, pericarditis, cellulitis, and, particularly in industrialized countries, epiglottitis. Hib disease occurs primarily in children aged < 2 years, particularly in infants. The disease burden is highest among those aged between 4 and 18 months. In unvaccinated populations, Hib is the dominant cause of non epidemic bacterial meningitis during the first year of life. Even with prompt and adequate antibiotic treatment, 3-20% of patients with Hib meningitis die. Where medical resources are limited, fatality rates for Hib meningitis may be much higher, and severe neurological sequelae are frequently observed in survivors (in up to 30-40%). [1]

Vaccines are the only public health tool capable of preventing the majority of cases of serious Hib disease. The Hib vaccines currently licensed for use in infants consist of the capsular polysaccharide of Hib conjugated to a protein carrier. The vaccines are formulated either as single antigens or as part of combination vaccines. Hib vaccines are safe and efficacious even when administered in early infancy. Randomized controlled trials have shown Hib vaccine to be highly effective against invasive Hib disease. A meta-analysis of Hib vaccine trials has shown the efficacy of vaccine against invasive Hib disease to be 84%, against Hib meningitis as 75%, and against Hib pneumonia as 69%. [2] Studies that used radiologically diagnosed pneumonia as the outcome measure after Hib vaccination have observed a reduction of approximately 20% in the incidence of serious pneumonia; the reduction in the incidence of clinical pneumonias was in the order of 4-5%. [1]

Introduction of Hib vaccine in routine childhood vaccination programs in more than 90 countries has shown that invasive Hib disease has been practically eliminated in many industrialized countries, and its incidence has been dramatically reduced in some parts of the developing world. Hib vaccination also reduces nasopharyngeal colonization with the organism, leading to substantially greater reduction in disease incidence than can be directly attributed to the effects of the vaccine. This indirect effect (herd immunity) has been amply demonstrated in several post introduction effectiveness studies in which near-elimination of the disease occurred in both industrialized and developing countries, even when vaccine coverage was suboptimal. [1]

 Studies from Asia



A case control study from Bangladesh has shown that three doses of Hib-containing vaccine reduced the risk of radiological pneumonia by 17-44%, depending on whether community or hospital controls were taken. [3] However, in a hamlet-randomized controlled double-blind vaccine-probe study in Lombok, Indonesia, radiological pneumonia was not affected but there was considerable effect against bacterial meningitis. [4]

 Cost-effectiveness



Studies from Kenya and Indonesia have established cost-effectiveness of Hib vaccine as cost of one death averted by use of Hib vaccine has been calculated to be $ 1197 and US$ 3102, respectively. [5],[6]

 World Health Organization Recommendations



World Health Organization (WHO) recommends three-dose primary series at the same time as the primary series of DTP and single dose for children aged >12 months who have not received their primary immunization series. Though in many industrialized countries, administering a booster dose during the child's second year of life has provided additional benefit; the need for and timing of a booster dose of Hib vaccine in developing countries require further study. [1]

WHO expert panel in 2004 also suggested further studies in Asian countries including strengthening of surveillance systems while introducing Hib vaccine in the national programs. [7]

 Situation in India



Some critics are against introduction of pentavalent vaccine in India, citing Hib disease burden to be lower in India. [8] However, facts are contrary to their objections. Child Health Epidemiology Reference Group has estimated around 408,000 deaths due to pneumonia in India. [9] This approximately corresponds to the figure arrived at by considering 27 million births per year and Under-Five Mortality Rate of 69 per 1000 live births and 22% deaths attributed to pneumonia. [10] Available data show that Hib is responsible for 13-19% of lower lung disease. [11],[12],[13] Considering this WHO estimate of 72,000 deaths due to Hib disease is quite reasonable.

 Recommendations for India



Based on available evidence, Hib is a priority disease in India. As a vaccine-probe study in Bangladesh has shown significant reduction in radiological pneumonia and Hib meningitis, whereas in Indonesia Hib vaccine has failed to show reduction in radiological pneumonia although it considerably reduced meningitis. There is need to assess its effectiveness in reduction of Hib disease in India, Hib pneumonia being a greater problem than other Hib disease. For this, it would be ideal to conduct a vaccine-probe study. However, these involve very high costs. In addition, based on recommendations of National Technical Advisory Group on Immunization (NTAGI), Government of India has already introduced pentavalent vaccine (DPT+HepatitisB+HiB) in Tamil Nadu and Kerala and there is a plan to introduce it in six other states. At this stage, it is prudent to institute radiological surveillance to assess the impact of introduction of Hib vaccine in reduction of pneumonia. This will require a baseline data for a given district, followed by ongoing surveillance data, and similar data from neighboring districts that have yet to introduce Hib vaccine and thus can serve as controls. Along with surveillance on pneumonia, surveillance on meningitis should also be taken up to assess the overall benefit of Hib vaccine.

Such studies should be taken up on a regional basis so that data generated are representative of the country. This will not only help to reconfirm the decision to introduce Hib vaccine in the National Immunization Schedule but also help in assessing the impact of program.

References

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4Gessner BD, Sutanto A, Linehan M, Djelantik IG, Fletcher T, Gerudug IK, et al. Incidences of vaccine-preventable Haemophilus influenzae type b pneumonia and meningitis in Indonesian children: Hamlet-randomised vaccine-probe trial. Lancet 2005;365:43-52.
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