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Invasive Haemophilus influenzae Infections after 3 Decades of Hib Protein Conjugate Vaccine Use. Clin Microbiol Rev 2021; 34:e0002821. [PMID: 34076491 DOI: 10.1128/cmr.00028-21] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Haemophilus influenzae serotype b (Hib) was previously the most common cause of bacterial meningitis and an important etiologic agent of pneumonia in children aged <5 years. Its major virulence factor is the polyribosyl ribitol phosphate (PRP) polysaccharide capsule. In the 1980s, PRP-protein conjugate Hib vaccines were developed and are now included in almost all national immunization programs, achieving a sustained decline in invasive Hib infections. However, invasive Hib disease has not yet been eliminated in countries with low vaccine coverage, and sporadic outbreaks of Hib infection still occur occasionally in countries with high vaccine coverage. Over the past 2 decades, other capsulated serotypes have been recognized increasingly as causing invasive infections. H. influenzae serotype a (Hia) is now a major cause of invasive infection in Indigenous communities of North America, prompting a possible requirement for an Hia conjugate vaccine. H. influenzae serotypes e and f are now more common than serotype b in Europe. Significant year-to-year increases in nontypeable H. influenzae invasive infections have occurred in many regions of the world. Invasive H. influenzae infections are now seen predominantly in patients at the extremes of life and those with underlying comorbidities. This review provides a comprehensive and critical overview of the current global epidemiology of invasive H. influenzae infections in different geographic regions of the world. It discusses those now at risk of invasive Hib disease, describes the emergence of other severe invasive H. influenzae infections, and emphasizes the importance of long-term, comprehensive, clinical and microbiologic surveillance to monitor a vaccine's impact.
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Slack MPE. Long Term Impact of Conjugate Vaccines on Haemophilus influenzae Meningitis: Narrative Review. Microorganisms 2021; 9:886. [PMID: 33919149 PMCID: PMC8143157 DOI: 10.3390/microorganisms9050886] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/11/2021] [Accepted: 04/19/2021] [Indexed: 02/06/2023] Open
Abstract
H. influenzae serotype b (Hib) used to be the commonest cause of bacterial meningitis in young children. The widespread use of Hib conjugate vaccine has profoundly altered the epidemiology of H. influenzae meningitis. This short review reports on the spectrum of H. influenzae meningitis thirty years after Hib conjugate vaccine was first introduced into a National Immunization Program (NIP). Hib meningitis is now uncommon, but meningitis caused by other capsulated serotypes of H. influenzae and non-typeable strains (NTHi) should be considered. H. influenzae serotype a (Hia) has emerged as a significant cause of meningitis in Indigenous children in North America, which may necessitate a Hia conjugate vaccine. Cases of Hie, Hif, and NTHi meningitis are predominantly seen in young children and less common in older age groups. This short review reports on the spectrum of H. influenzae meningitis thirty years after Hib conjugate vaccine was first introduced into a NIP.
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Nisar MI, Jehan F, Shafiq Y, Lassi ZS, Zaidi AKM. Conjugate vaccines for preventing Haemophilus influenzae type b infections in children under 5 years of age. Hippokratia 2016. [DOI: 10.1002/14651858.cd010377.pub2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Muhammad I Nisar
- Aga Khan University Hospital; Division of Women and Child Health; Stadium Road PO Box 3500 Karachi Pakistan 74800
| | - Fyezah Jehan
- Aga Khan University Hospital; Division of Women and Child Health; Stadium Road PO Box 3500 Karachi Pakistan 74800
| | - Yasir Shafiq
- Aga Khan University Hospital; Department of Paediatrics and Child Health; Stadium Road PO Box 3500 Karachi Sindh Pakistan 74800
| | - Zohra S Lassi
- The University of Adelaide; The Robinson Research Institute; Adelaide South Australia Australia 5005
| | - Anita KM Zaidi
- Aga Khan University Hospital; Division of Women and Child Health; Stadium Road PO Box 3500 Karachi Pakistan 74800
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Clinical and Molecular Epidemiology of Childhood Invasive Nontypeable Haemophilus influenzae Disease in England and Wales. Pediatr Infect Dis J 2016; 35:e76-84. [PMID: 26569188 DOI: 10.1097/inf.0000000000000996] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
INTRODUCTION In countries with established Haemophilus influenzae type b (Hib) immunization programs, nontypeable H. influenzae (NTHi) is now responsible for nearly all invasive H. influenzae cases across all age groups. METHODS Public Health England (PHE) conducts enhanced national surveillance of invasive H. influenzae disease in England and Wales. Invasive NTHi isolates submitted to Public Health England from children of ages 1 month to 10 years during 2003-2010 were characterized by multilocus sequence typing (MLST). Detailed clinical information was obtained for all laboratory-confirmed cases of invasive NTHi disease in children during 2009-2013. RESULTS In England and Wales, there were 7797 cases of invasive H. influenzae disease diagnosed during 2000-2013 and 1585 (20%) occurred in children aged 1 month to 10 years, where NTHi was responsible for 31-51 cases (incidence, 0.53-0.92/100,000) annually. Detailed clinical follow-up of 214 confirmed NTHi cases diagnosed in this age-group during 2009-2013 revealed that 52% (n = 111) occurred in <2-year-old and 52% (n=110) had comorbidity. Bacteremic pneumonia was the most common clinical presentation (n = 99, 46%), 16% (n = 34) required intensive care and 11% (n = 23) died. Characterization by biotyping and MLST of 316 NTHi strains from children with invasive disease during 2003-2010 revealed a genetically heterogeneous population (155 MLSTs) with diverse biotypes and no association with comorbidity status, clinical disease or outcome. CONCLUSIONS The high level of genetic diversity in invasive NTHi strains highlights the difficulties in developing an effective vaccine against this pathogen.
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Konini A, Moghadas SM. Modelling the impact of vaccination on curtailing Haemophilus influenzae serotype 'a'. J Theor Biol 2015; 387:101-10. [PMID: 26453974 DOI: 10.1016/j.jtbi.2015.09.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 08/16/2015] [Accepted: 09/25/2015] [Indexed: 12/16/2022]
Abstract
Haemophilus influenzae serotype a (Hia) is a human-restricted bacterial pathogen transmitted via direct contacts with an infectious individual. Currently, there is no vaccine available for prevention of Hia, and the disease is treated with antibiotics upon diagnosis. With ongoing efforts for the development of an anti-Hia protein-polysaccharide conjugated vaccine, we sought to investigate the effect of vaccination on curtailing Hia infection. We present the first stochastic model of Hia transmission and control dynamics, and parameterize it using available estimates in the literature. Since both naturally acquired and vaccine-induced immunity wane with time, model simulations show three important results. First, vaccination of only newborns cannot eliminate the pathogen from the population, even when a booster program is implemented with a high coverage. Second, achieving and maintaining a sufficiently high level of herd immunity for pathogen elimination requires vaccination of susceptible individuals in addition to a high vaccination coverage of newborns. Third, for a low vaccination rate of susceptible individuals, a high coverage of booster dose may be needed to raise the level of herd immunity for Hia eradication. Our findings highlight the importance of vaccination and timely boosting of the individual׳s immunity within the expected duration of vaccine-induced protection against Hia. When an anti-Hia vaccine becomes available, enhanced surveillance of Hia incidence and herd immunity could help determine vaccination rates and timelines for booster doses necessary to eliminate Hia from affected populations.
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Affiliation(s)
- Angjelina Konini
- Department of Mathematics and Statistics, Agent-Based Modelling Laboratory, York University, Toronto, Ontario, Canada M3J 1P3.
| | - Seyed M Moghadas
- Department of Mathematics and Statistics, Agent-Based Modelling Laboratory, York University, Toronto, Ontario, Canada M3J 1P3
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Trends in the epidemiology of invasive Haemophilus influenzae disease in Queensland, Australia from 2000 to 2013: what is the impact of an increase in invasive non-typable H. influenzae (NTHi)? Epidemiol Infect 2015; 143:2993-3000. [PMID: 25762194 DOI: 10.1017/s0950268815000345] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Following the introduction of vaccination against Haemophilus influenzae type b (Hib), cases of invasive encapsulated Hib disease have decreased markedly. This study aimed to examine subsequent epidemiological trends in invasive H. influenzae disease in Queensland, Australia and in particular, assess the clinical impact and public health implications of invasive non-typable H. influenzae (NTHi) strains. A multicentre retrospective study was conducted from July 2000 to June 2013. Databases of major laboratories in Queensland including Queensland Forensic and Scientific Services (jurisdictional referral laboratory for isolate typing) were examined to identify cases. Demographic, infection site, Indigenous status, serotype, and mortality data were collected. In total, 737 invasive isolates were identified, of which 586 (79·5%) were serotyped. Hib, NTHi and encapsulated non-b strains, respectively, constituted 12·1%, 69·1% and 18·8% of isolates. The predominant encapsulated non-b strains were f (45·5%) and a (27·3%) serotypes. Of isolates causing meningitis, 48·9% were NTHi, 14·9% Hib, 14·9% Hie, 10·6% Hif, 6·4% Hia and 4·3% were untyped. During the study period, there was an increase in the incidence of invasive NTHi disease (P = 0·007) with seasonal peaks in winter and spring (P 0·001) and Hib (P = 0·039) than non-Indigenous patients. In Queensland, invasive H. influenzae disease is now predominantly encountered in adults and most commonly caused by NTHi strains with demonstrated pathogenicity extending to otherwise young or immunocompetent individuals. Routine public health notification of these strains is recommended and recent available immunization options should be considered.
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Tan YC, Gill AK, Kim KS. Treatment strategies for central nervous system infections: an update. Expert Opin Pharmacother 2014; 16:187-203. [PMID: 25328149 DOI: 10.1517/14656566.2015.973851] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Central nervous system infection continues to be an important cause of mortality and morbidity worldwide. Our incomplete knowledge on the pathogenesis of how meningitis-causing pathogens cause CNS infection and emergence of antimicrobial resistance has contributed to the mortality and morbidity. An early empiric antibiotic treatment is critical for the management of patients with bacterial meningitis, but early recognition of bacterial meningitis continues to be a challenge. AREAS COVERED This review gives an overview on current therapeutic strategies for CNS infection with a focus on recent literature since 2010 on bacterial meningitis. Bacterial meningitis is a medical emergency, requiring early recognition and treatment. The selection of appropriate empiric antimicrobial regimen, after incorporating the epidemiology of bacterial meningitis, impact of vaccination, emergence of antimicrobial-resistant bacteria, role of adjunctive therapy and the current knowledge on the pathogenesis of meningitis and associated neuronal injury are covered. EXPERT OPINION Prompt treatment of bacterial meningitis with an appropriate antibiotic is essential. Optimal antimicrobial treatment of bacterial meningitis requires bactericidal agents able to penetrate the blood-brain barrier, with efficacy in cerebrospinal fluid. Emergence of CNS-infecting pathogens with resistance to conventional antibiotics has been increasingly recognized, but development of new antibiotics has been limited. More complete understanding of the microbial and host factors that are involved in the pathogenesis of bacterial meningitis and associated neurologic sequelae is likely to help in developing new strategies for the prevention and therapy of bacterial meningitis.
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Affiliation(s)
- Ying Ching Tan
- Johns Hopkins University School of Medicine, Division of Pediatric Infectious Diseases , 200 North Wolfe Street, Baltimore, MD 21287 , USA
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Van Eldere J, Slack MPE, Ladhani S, Cripps AW. Non-typeable Haemophilus influenzae, an under-recognised pathogen. THE LANCET. INFECTIOUS DISEASES 2014; 14:1281-92. [PMID: 25012226 DOI: 10.1016/s1473-3099(14)70734-0] [Citation(s) in RCA: 228] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Non-typeable Haemophilus influenzae (NTHi) is a major cause of mucosal infections such as otitis media, sinusitis, conjunctivitis, and exacerbations of chronic obstructive pulmonary disease. In some regions, a strong causal relation links this pathogen with infections of the lower respiratory tract. In the past 20 years, a steady but constant increase has occurred in invasive NTHi worldwide, with perinatal infants, young children, and elderly people most at risk. Individuals with underlying comorbidities are most susceptible and infection is associated with high mortality. β-lactamase production is the predominant mechanism of resistance. However, the emergence and spread of β-lactamase-negative ampicillin-resistant strains in many regions of the world is of substantial concern, potentially necessitating changes to antibiotic treatment guidelines for community-acquired infections of the upper and lower respiratory tract and potentially increasing morbidity associated with invasive NTHi infections. Standardised surveillance protocols and typing methodologies to monitor this emerging pathogen should be implemented. International scientific organisations need to raise the profile of NTHi and to document the pathobiology of this microbe.
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Affiliation(s)
- Johan Van Eldere
- Department of Microbiology and Immunology, Catholic University Leuven, Belgium; Clinical Department of Laboratory Medicine, University Hospital Leuven, Belgium.
| | - Mary P E Slack
- WHO Collaborating Centre for Haemophilus influenzae, Respiratory and Vaccine Preventable Bacteria Reference Unit, Microbiology Services, Public Health England, Colindale, London, UK
| | - Shamez Ladhani
- Immunisation, Hepatitis and Blood Safety Department, Health Protection Services, Public Health England, Colindale, London, UK
| | - Allan W Cripps
- School of Medicine, Griffith Health Institute, Griffith University, Gold Coast, QLD, Australia
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Martin NG, Sadarangani M, Pollard AJ, Goldacre MJ. Hospital admission rates for meningitis and septicaemia caused by Haemophilus influenzae, Neisseria meningitidis, and Streptococcus pneumoniae in children in England over five decades: a population-based observational study. THE LANCET. INFECTIOUS DISEASES 2014; 14:397-405. [DOI: 10.1016/s1473-3099(14)70027-1] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Programming of the lung in early life by bacterial infections predisposes to chronic respiratory disease. Clin Obstet Gynecol 2014; 56:566-76. [PMID: 23722921 DOI: 10.1097/grf.0b013e3182993a0c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
There is emerging evidence that chronic respiratory diseases such as asthma and emphysema may originate in early life. Respiratory infections with certain bacterial pathogens such as Chlamydia, Haemophilus influenzae and Streptococcus pneumoniae in early life may promote permanent deleterious changes in immunity, lung structure, and function that predispose to, or increase the severity of chronic respiratory diseases in later life. For example, these infections increase immune responses, which drive subsequent asthma pathogenesis. Targeting the pathways involved with specific inhibitors or agonists may prevent these consequences of early-life infection. Vaccination and immunomodulatory therapies that control the infections and their sequelae may also be efficacious.
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Gkentzi D, Collins S, Slack MPE, Ladhani SN. Childhood Haemophilus influenzae related deaths in England and Wales. J Public Health (Oxf) 2013. [DOI: 10.1007/s10389-013-0576-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Maiden MCJ. The impact of protein-conjugate polysaccharide vaccines: an endgame for meningitis? Philos Trans R Soc Lond B Biol Sci 2013; 368:20120147. [PMID: 23798695 PMCID: PMC3720045 DOI: 10.1098/rstb.2012.0147] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The development and implementation of conjugate polysaccharide vaccines against invasive bacterial diseases, specifically those caused by the encapsulated bacteria Neisseria meningitidis, Haemophilus influenzae and Streptococcus pneumoniae, has been one of the most effective public health innovations of the last 25 years. These vaccines have resulted in significant reductions in childhood morbidity and mortality worldwide, with their effectiveness due in large part to their ability to induce long-lasting immunity in a range of age groups. At the population level this immunity reduces carriage and interrupts transmission resulting in herd immunity; however, these beneficial effects can be counterbalanced by the selection pressures that immunity against carriage can impose, potentially promoting the emergence and spread of virulent vaccine escape variants. Studies following the implementation of meningococcal serogroup C vaccines improved our understanding of these effects in relation to the biology of accidental pathogens such as the meningococcus. This understanding has enabled the refinement of the implementation of conjugate polysaccharide vaccines against meningitis-associated bacteria, and will be crucial in maintaining and improving vaccine control of these infections. To date there is little evidence for the spread of virulent vaccine escape variants of the meningococcus and H. influenzae, although this has been reported in pneumococci.
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Affiliation(s)
- Martin C J Maiden
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
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Abstract
BACKGROUND Children with petechial rash are more likely to undergo invasive diagnostics, to be treated with antibiotics for potential bacterial infection and to be hospitalized. However, viruses have also been associated with petechial rash. Nonetheless, a systematic analysis of viral infections with modern available techniques as quantitative real-time polymerase chain reaction in the context of petechial rash is lacking. The purpose of this pediatric study was to prospectively uncover viral pathogens that may promote the emergence of petechiae and to analyze the correlation with the clinical characteristics and course. METHODS We conducted a prospective study in children (0 to 18 years) presenting with petechiae and signs or symptoms of infection at the emergency department between November 2009 and March 2012. In nasopharyngeal aspirates the following viruses were analyzed by quantitative real-time polymerase chain reaction: cytomegalovirus, Epstein-Barr virus, parvovirus B19, influenza A and B, parainfluenza viruses, human respiratory syncytial virus A and B, human metapneumovirus, rhinovirus, enterovirus, adenovirus, human coronavirus OC43, 229E, NL63 and human bocavirus. RESULTS A viral pathogen was identified in 67% of the analyzed 58 cases with petechial rash. Virus positive patients showed a significantly higher incidence of lower respiratory tract infections. Forty-one percent were viral coinfections, which were significantly younger than virus negative patients, had a higher leukocyte count and were hospitalized for a longer time. CONCLUSIONS A petechial rash is frequently associated viral single- and coinfections and can rapidly be identified via quantitative real-time polymerase chain reaction.
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Jones C, Pollock L, Barnett SM, Battersby A, Kampmann B. Specific antibodies against vaccine-preventable infections: a mother-infant cohort study. BMJ Open 2013; 3:e002473. [PMID: 23585389 PMCID: PMC3641500 DOI: 10.1136/bmjopen-2012-002473] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Revised: 03/04/2013] [Accepted: 03/12/2013] [Indexed: 11/25/2022] Open
Abstract
OBJECTIVES To determine maternal and neonatal specific antibody levels to selected vaccine-preventable infections (pertussis, Haemophilus influenzae type b (Hib), tetanus and pneumococcus). DESIGN Prospective cohort study. SETTING A UK secondary care maternity unit (March 2011-January 2012). PARTICIPANTS Mothers and infants within 72 h of delivery were eligible. Unwell individuals, mothers less than 18 years of age, and infants born at less than 36 weeks gestation, or weighing less than 2500 g, were excluded. HIV-infected mothers were included. 112 mother-infant pairs were recruited. Samples from 111 mothers and 109 infants (108 pairs) were available for analysis. OUTCOME MEASURES Specific antibody levels were determined using standard commercial ELISAs. Specific antibody to pertussis antigens (PT and FHA) of >50 IU/ml, defined as 'positive' by the test manufacturer, were interpreted as protective. Antitetanus antibody titres >0.1 IU/ml and anti-Hib antibody titres >1 mg/l were regarded as protective. RESULTS Only 17% (19/111) of women exhibited a protective antibody response against pertussis. 50% (56/111) of women had levels of antibody protective against Hib and 79% (88/111) against tetanus. There was a strong positive correlation between maternal-specific and infant-specific antibodies' responses against pertussis (rs=0.71, p<0.001), Hib (rs=0.80, p<0.001), tetanus (rs=0.90, p<0.001) and pneumococcal capsular polysaccharide (rs=0.85, p<0.001). Only 30% (33/109) and 42% (46/109) of infants showed a protective antibody response to pertussis and Hib, respectively. Placental transfer (infant:mother ratio) of specific IgG to pertussis, Hib, pneumococcus and tetanus was significantly reduced from HIV-infected mothers to their HIV-exposed, uninfected infants (n=12 pairs) compared with HIV-uninfected mothers with HIV-unexposed infants (n=96 pairs) by 58% (<0.001), 61% (<0.001), 28% (p=0.034) and 32% (p=0.035), respectively. CONCLUSIONS Low baseline antibody levels against pertussis in this cohort suggest the recently implemented UK maternal pertussis immunisation programme has potential to be effective.
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Affiliation(s)
- Christine Jones
- Academic Department of Paediatrics, Imperial College London, London, UK
- Paediatric Infectious Diseases Research Group, St George's, University of London, London, UK
| | - Louisa Pollock
- Academic Department of Paediatrics, Imperial College London, London, UK
| | - Sara M Barnett
- Academic Department of Paediatrics, Imperial College London, London, UK
| | - Anna Battersby
- Academic Department of Paediatrics, Imperial College London, London, UK
| | - Beate Kampmann
- Academic Department of Paediatrics, Imperial College London, London, UK
- Vaccinology Theme, Medical Research Council Unit – The Gambia, Fajara, The Gambia
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The burden of nonencapsulated Haemophilus influenzae in children and potential for prevention. Curr Opin Infect Dis 2012; 25:266-72. [PMID: 22561999 DOI: 10.1097/qco.0b013e32835310a4] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW In countries with established Haemophilus influenzae serotype b (Hib) immunization programmes, nonencapsulated H. influenzae (ncHi) is responsible for most invasive H. influenzae infections across all age groups and is associated with higher case fatality. A pneumococcal conjugate vaccine has recently been licensed, which may potentially also protect against invasive H. influenzae infections. RECENT FINDINGS Invasive ncHi disease is uncommon in childhood but has a much higher incidence in the first month of life. Most neonates with invasive ncHi infections are born prematurely and develop septicaemia in the first 48 h of life which can be fatal. After this period, invasive ncHi incidence falls rapidly and remains low throughout childhood. Most infants and children who develop invasive ncHi disease have significant underlying comorbidities, particularly neurological disease, malignancy and other conditions requiring immunosuppressive therapy. Although characteristically associated with respiratory tract infections, at least a quarter of invasive ncHi infections present with meningitis. SUMMARY A vaccine against ncHi could have an important preventive role in children with comorbidities. Future studies should focus on assessing specific risk factors for neonatal and childhood ncHi disease and long-term outcomes of children with invasive ncHi meningitis.
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Ladhani SN. Two decades of experience with the Haemophilus influenzae serotype b conjugate vaccine in the United Kingdom. Clin Ther 2012; 34:385-99. [PMID: 22244051 DOI: 10.1016/j.clinthera.2011.11.027] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Revised: 11/16/2011] [Accepted: 11/23/2011] [Indexed: 11/30/2022]
Abstract
BACKGROUND The Haemophilus influenzae serotype b (Hib) conjugate vaccine was introduced into the UK national childhood immunization program in 1992 after clinical trials reported the vaccine to be highly immunogenic in infants as young as two months of age. OBJECTIVE The goal of this study was to describe and comment on the impact of routine Hib immunization on the epidemiology of invasive Hib disease in the United Kingdom. In addition, the development of Hib polysaccharide and conjugate vaccines was reviewed. METHODS A literature search was conducted of PubMed for invasive Hib disease epidemiology in the United Kingdom. The UK Health Protection Agency Web site was also searched for relevant publications. RESULTS The incidence of invasive Hib incidence in children aged <5 years fell from 21/100,000 to 44/100,000 in the prevaccine era to 0.63/100,000 in 1998, with an estimated vaccine failure rate of 2.2/100,000 vaccinees. After 1999, however, invasive Hib disease increased, particularly in toddlers, and peaked in 2003. Potential reasons for the resurgence included a greater-than-expected decline in Hib antibodies after primary immunization, waning of herd immunity offered by the initial catch-up campaign, and use of a less immunogenic Hib combination vaccine containing acellular pertussis in 2000-2001. In response to the resurgence, a Hib combination vaccine containing whole-cell pertussis was reintroduced in 2002, followed by a childhood Hib booster campaign in 2003. In 2004, the recommended infant vaccine was changed to a different Hib/acellular pertussis combination vaccine containing inactivated polio, which had a satisfactory Hib response, was less reactogenic, and eliminated the risk of vaccine-associated paralytic poliomyelitis. This action was followed by introduction of a routine 12-month Hib booster in 2006. Together, these measures led to a decline in invasive Hib disease across all age groups. In 2010, there were only 30 invasive Hib cases, with 6 reported in children aged <5 years and no deaths in this age group since 2007. CONCLUSIONS Control of Hib disease is currently the best that has been achieved since the introduction of the routine Hib vaccination almost 20 years ago.
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