Strategies for immunization against invasive Haemophilus influenzae type b infection (original) (raw)
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Expert Review of Vaccines, 2020
Introduction: Prior to implementation of Haemophilus influenzae type b (Hib)-conjugate vaccination programs in the 1990s, Hib was the commonest cause of bacterial meningitis in children aged <5 years. While the burden of all Hib disease has significantly decreased in the post-vaccination era, Hib still accounted for >29,000 deaths worldwide in children aged <5 years in 2015. Areas covered: We reviewed literature data on the most widely used Hib vaccines and vaccination strategies which led to the global prevention and control of Hib disease and aim to highlight important factors for continued disease control and elimination in the future. Expert commentary: More than 90% of countries worldwide have implemented Hib-conjugate vaccination in their national immunization programs. Vaccines containing Hib polyribosylribitol phosphate (PRP) conjugated with tetanus toxoid (Hib-TT) are the most commonly used. Neisseria meningitidis outer membrane protein complex of PRP (Hib-OMP) is also used. Although the kinetics of the immune response varies with Hib vaccine and schedule used, high control of Hib disease was observed in all settings/scenarios. Further improving global Hib vaccination coverage may result in disease elimination.
Seminars in Pediatric Infectious Diseases, 1998
Haemophilus mfluenzae is a small gram-negative pleomorphic coccobacillus. The H influenzaetype b (Hib) strain is especially important because, prior to the advent of effective Hib vaccines, the organism was the cause of 95% to 98% of severs invasive infections, including meningitis, epiglottitis, cellulitis, sepsis, pneumonia, and osteomyelitis, in children less than 5 years of age. An important microbiologic feature of H influenzae is its development of resistance to a wide variety of antibiotics, including sulfonamides, trimethoprim-sulfamethoxazole, erythromycin, tetracycline, and penicillin. Ampicillin resistance is now widespread, ranging between 5% and 40% of all isolates in various parts of the world. The current mainstays of treatment are third-generation cephalosporins, but the potential for increased resistance to them, as well as other factors, has underscored the need for prophylactic measures. Since the early 1970s, when the capsular polysaccharide of Hib was purified, characterized, and shown to be immunogenic, tremendous strides have been made worldwide to immunize children against the organism and to irradicate the bacteria. A steady decline in the incidence of Hib diseases has occurred since the introduction in 1990 of Hib conjugate vaccines for infants. Because of this rapid decline, Hib diseases among children less than 5 years of age is targeted for elimination in the United States. This article provides an overview of the discovery and characterization of the organism and a review of the literature on the impact that the Hib vaccines have had on morbidity and mortality rates among children less than 5 years of age.
Haemophilus influenzae type B conjugate vaccines
Annals of Pharmacotherapy
To review the epidemiology of Haemophilus influenzae type b (Hib) disease, the first Hib vaccine and its limitations, the characteristics and clinical efficacy of the newer conjugate vaccines, and the current recommendations for administration of Hib vaccines. Pertinent literature was identified via a MEDLINE search. Additionally, references cited in published articles were used as data sources. Studies describing the epidemiology of Hib disease and the efficacy and/or immunogenicity of the Hib vaccines are reviewed. Serious invasive disease secondary to Hib infection causes significant morbidity and mortality in children between the ages of three months and five years. The original Hib vaccine was found to be ineffective in stimulating an adequate immune response in children younger than two years of age. The new Hib conjugate vaccines provide superior efficacy and immunogenicity compared with the original unconjugated vaccine. They stimulate an immune response that is distinctly different from that elicited by the original vaccine. Two vaccine products are currently licensed for use in children as young as two months of age, thus conferring immunity to those children at highest risk for Hib disease. The new Hib conjugate vaccines provide excellent efficacy and, when used as recommended, may significantly reduce the incidence of invasive Hib disease and its sequelae.
Human Vaccines, 2009
Hib is estimated to cause at least 3 million cases of serious disease every year as well as approximately 386,000 deaths. 2 The burden of Hib disease is proved in large studies conducted in Africa, Asia and Latin America where the vaccine was found to be useful in reducing childhood infections. 3-5 In view of demonstrated safety and efficacy, World Health Organization (WHO) recommends that conjugate Hib vaccines should be included in all routine infant immunization program. 2 Hib vaccination also reduces nasopharyngeal colonization with the organism, leading to substantial 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 efficacy studies in which near-elimination of Hib disease occurred even when vaccine coverage was sub-optimal. 2,6-8 The successful reduction of Hib disease including pneumonia and meningitis has been observed in Hib vaccine recipients in developing countries like Gambia, Uganda, Kenya and Bangladesh. 9-12 In these countries, the Hib conjugate vaccine was made available from vaccine manufacturers and/or global organizations aiming at improved immunization services. The actual number of children receiving a third dose of the vaccine globally has increased from 8% of the world's surviving infants in 1999 to 22% in 2006. 13 The epidemiology of Hib infections in India has revealed that the infection is prevalent, even in India. Hib is a leading cause of bacterial childhood meningitis and important cause of severe pneumonia, in India. Approximately, 19% (410,000) of under 5 deaths in India are due to pneumonia. 14 India accounts for almost 40% of worldwide childhood pneumonia cases. However, experts opine that these estimates are underestimated. The case-fatality rate for Hib meningitis was 11% overall, in a study conducted in India. 15 A study showed that about 30% of Indian children who survived Hib meningitis, suffered from major disabilities. 16 There is an increase in consensus among experts that estimates of Hib pneumonia rates in India are underestimated. A large percent of Indian children are thought to be at a high risk due to increasing resistance to antibiotics as well as to limited access to health care facilities. As per hospital data, 30-45% cases of meningitis and 8-12% cases of pneumonitis in India are due to Hib. It is estimated that annual incidence of Hib In view of the need for a cost effective Haemophilus influenzae type b (Hib) conjugate vaccine, a lyophilized vaccine as capsular polysaccharide (PRP) conjugated to tetanus toxoid (Sii HibPRO) was indigenously developed by Serum Institute of India Ltd., Pune (SIIL). From 2004-07, this new vaccine underwent a series of clinical studies before its licensure by National Regulatory Authority (NRA). This paper discusses the results obtained during the clinical development of this vaccine. On finding the vaccine to be safe in animal toxicity studies, a Phase I single dose study was carried out to assess the safety profile of Sii HibPRO in healthy adult male volunteers. Subsequently, in Phase III pre-licensure study, immunogenicity and safety of Sii HibPRO was assessed and compared with Hib tetanus conjugate vaccine (Act-HIB) of Aventis, France. Immunogenicity was evaluated based upon serum anti-PRP IgG antibody concentrations by ELISA at prevaccination and one month each after the second and third dose. Safety was evaluated by recording details of adverse events after each dose of the vaccine. Postvaccination after the third dose, there was 100% seroprotection (anti PRP IgG titre ≥ 0.15 μg/ml) in both the groups. Long term protection (≥1 μg/ml) was achieved in 95.2% and 98.06% infants in Sii HibPRO and Act-HIB groups, respectively. At 15 months, prior to booster dose, 30 children in each group were evaluated and all were found to be seroprotected. Post booster, all of them responded with a strong boost response. Safety of Sii HibPRO was re-established in the post marketing surveillance in which 2,739 doses were administered to 1,029 infants, in 23 cities across India.
Safety and immunogenicity of two Haemophilus influenzae type b conjugate vaccines
South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde, 2004
OBJECTIVES Haemophilus influenzae type b (Hib) infection remains a major public health problem in the developing world. We evaluated the safety and immunogenicity of a new PRP-CRM197 conjugate Hib vaccine (Vaxem Hib, Chiron Vaccines), compared with the HibTITER vaccine (Wyeth-Lederle Vaccines), following the World Health Organisation (WHO)'s accelerated schedule which allows 4-week intervals between doses. STUDY DESIGN A phase II, observer-blind, multicentre, randomised, controlled, non-inferiority study. METHODS In total, 331 babies were immunised with either Vaxem Hib (N = 167) or HibTITER (N = 164) vaccine at 6, 10 and 14 weeks of age, in parallel with oral polio, diphtheriatetanus-pertussis and hepatitis B vaccines. Post-immunisation reactions were recorded after each immunisation and at follow-up visits. Anti-polyribosylribitol phosphate (PRP) antibodies were measured using enzyme-linked immunosorbent assays (ELISAs) before and 1 month after the third immunisation. RESULTS ...
Prevention of invasive Haemophilus influenzae type b disease: lessons from vaccine efficacy trials
Vaccine, 1991
To assess vaccines, multiple laboratory investigations and immunogenicity studies are conducted but the ultimate tests of the effectiveness of a vaccine are field trials that evaluate disease prevention. Immunogenicity studies are often used as a surrogate for protection, but it is often difficult to determine precisely the level of antibody needed for protection and it is not always clear what immunologic factors most determine protection. However, efficacy trials are difficult to conduct well and there are only a limited number of ways to perform such studies. Nonetheless, the results of efficacy studies are essential for the appropriate selection of the best Hib vaccines and to establish recommendations for optimal use. The first Hib vaccine, the PRP (polyribosylribitol phosphate) polysaccharide vaccine, was shown by several efficacy studies to have no protective efficacy in young infants, and to have only limited, if any, efficacy in older children. The first Hib polysaccharide ...