Incidence Of Hib Meningitis Research Articles

Estimating the global and regional burden of meningitis in children caused by Haemophilus influenzae type b: A systematic review and meta-analysis.

BackgroundHaemophilus influenzae Type B (Hib) meningitis caused significant public health concern for children. Recent assessment in 2015 suggests vaccination has virtually eliminated invasive Hib diseases. However, many countries launched their programs after 2010, and few are yet to establish routine Hib immunisations. We therefore aimed to update the most recent global burden of Hib meningitis before the impact of COVID-19 pandemic, from 2010 to 2020, in order to aid future public health policies on disease management and prevention.MethodsEpidemiological data regarding Hib meningitis in children <5 years old were systematically searched and evaluated from PubMed and Scopus in August, 2020. We included studies published between 2010 and 2019 that reported incidence, prevalence, mortality, or case-fatality-ratio (CFR), and confirmation of meningitis by cerebrospinal fluid culture, with a minimum one year study period and ten cases. Each data was stratified by one study-year. Median study-year was used if information was not available. Quality of all studies were assessed using our adapted assessment criteria from Grading of Recommendations Assessment, Development and Evaluation (GRADE) and Study Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies from National Heart, Lung and Blood Institute (NHLBI). We constructed and visually inspected a funnel plot of standard error by the incidence rate and performed an Egger’s regression test to statistically assess publication bias. To ascertain incidence and CFR, we performed generalised linear mixed models on crude individual study estimates. Heterogeneity was assessed using I-squared statistics whilst further exploring heterogeneity by performing subgroup analysis.Results33 studies were identified. Pooled incidence of global Hib meningitis in children was 1.13 per 100 000-child-years (95% confidence interval (CI) = 0.80-1.59). Southeast Asian Region (SEAR) of World Health Organisation (WHO) region reported the highest incidence, and European Region (EUR) the lowest. Considering regions with three or more data, Western Pacific Region (WPR) had the highest incidence rate of 5.22 (95% CI = 3.12-8.72). Post-vaccination incidence (0.67 cases per 100 000-child-years, 95% CI = 0.48-0.94) was dramatically lower than Pre-vaccination incidence (4.84 cases per 100 000-child-years, 95% CI = 2.95-7.96). Pooled CFR in our meta-analysis was 11.21% (95% CI = 7.01-17.45). Eastern Mediterranean Region (EMR) had the highest CFR (26.92, 95% CI = 13.41-46.71) while EUR had the lowest (4.13, 95% CI = 1.73-9.54). However, considering regions with three or more data, African Region (AFR) had the highest CFR at 21.79% (95% CI = 13.65-32.92). Before the coronavirus disease 2019 (COVID-19) impact, the estimation for global Hib meningitis cases in 2020 is 7645 and 857 deaths.ConclusionsGlobal burden of Hib meningitis has markedly decreased, and most regions have implemented vaccination programs. Extrapolating population-at-risk from studies has possibly led to an underestimation. Continuous surveillance is necessary to monitor vaccination impact, resurgence, vaccine failures, strain variance, COVID-19 impact, and to track improvement of regional and global Hib meningitis mortality.

Impact of routine vaccination against Haemophilus influenzae type b in The Gambia: 20 years after its introduction.

BackgroundIn 1997, The Gambia introduced three primary doses of Haemophilus influenzae type b (Hib) conjugate vaccine without a booster in its infant immunisation programme along with establishment of a population-based surveillance on Hib meningitis in the West Coast Region (WCR). This surveillance was stopped in 2002 with reported elimination of Hib disease. This was re-established in 2008 but stopped again in 2010. We aimed to re-establish the surveillance in WCR and to continue surveillance in Basse Health and Demographic Surveillance System (BHDSS) in the east of the country to assess any shifts in the epidemiology of Hib disease in The Gambia.MethodsIn WCR, population-based surveillance for Hib meningitis was re-established in children aged under-10 years from 24 December 2014 to 31 March 2017, using conventional microbiology and Real Time Polymerase Chain Reaction (RT-PCR). In BHDSS, population-based surveillance for Hib disease was conducted in children aged 2-59 months from 12 May 2008 to 31 December 2017 using conventional microbiology only. Hib carriage survey was carried out in pre-school and school children from July 2015 to November 2016.ResultsIn WCR, five Hib meningitis cases were detected using conventional microbiology while another 14 were detected by RT-PCR. Of the 19 cases, two (11%) were too young to be protected by vaccination while seven (37%) were unvaccinated. Using conventional microbiology, the incidence of Hib meningitis per 100 000-child-year (CY) in children aged 1-59 months was 0.7 in 2015 (95% confidence interval (CI) = 0.0-3.7) and 2.7 (95% CI = 0.7-7.0) in 2016. In BHDSS, 25 Hib cases were reported. Nine (36%) were too young to be protected by vaccination and five (20%) were under-vaccinated for age. Disease incidence peaked in 2012-2013 at 15 per 100 000 CY and fell to 5-8 per 100 000 CY over the subsequent four years. The prevalence of Hib carriage was 0.12% in WCR and 0.38% in BHDSS.ConclusionsAfter 20 years of using three primary doses of Hib vaccine without a booster Hib transmission continues in The Gambia, albeit at low rates. Improved coverage and timeliness of vaccination are of high priority for Hib disease in settings like Gambia, and there are currently no clear indications of a need for a booster dose.

Acute meningitis and encephalitis syndrome surveillance disease burden in four China prefectures

Objectives: To explore acute meningitis and encephalitis syndrome (AMES) surveillance in 4 China prefectures, to understand the epidemiological features and disease burden of neisseria meningitides (Nm) meningitis, streptococcus pneumoniae (Sp) meningitis, haemophilus influenza type b (Hib) meningitis and Japanese encephalitis and provide evidence for related disease prevention and control. Methods: AMES surveillance were conducted in Jinan, Shandong Province and Yichang, Hubei Province in September 2006, and in 13 districts of Shijiazhuang, Hebei Province and Guigang City, Guangxi Zhuang Autonomous Region in April 2007. Six hospitals in each city were selected as monitoring pilot hospitals to carry out reports of suspected cases of acute meningitis and encephalitis, case investigation, blood specimens and cerebrospinal fluid specimen collection, anti-JEV IgM antibody enzyme-linked immunosorbent assay, Nm, Sp and Hib culture and polymerase chain reaction detection, etc. According to the age group, the incidence of bacterial meningitis and Japanese encephalitis in local residents <20 years old was estimated. Results: From 2006 to 2013, a total of 19 423 surveillance cases were reported in four cities, of which 11 071 (56.99%) were reported in the pilot hospitals. Of the 11 071 cases, 5 315 were tested for bacteriology and 9 180 were tested for anti-JEV IgM antibodies. Among the bacteriological tests, 176 cases were positive, including 75 cases of Nm positive, 91 cases of Sp positive and 10 cases of Hib positive. The incidence of three bacterial meningitis is estimated for people under 20 years old, with estimated incidence of Nm, Sp and Hib meningitis in children <5 years old was 0.46/100 000-0.71/100 000, 0.34/100 000-0.83/100 000 and 0.32/100 000-0.57/100 000 respectively; the estimated incidence of Nm and Sp meningitis in children aged 5-9 years was 0.59/100 000-1.14/100 000 and 0.50/100 000-1.66/100 000 respectively. In 732 cases of positive JE cases, the positive detection rates of <5 years old, 40-49 years old and ≥50 years old were 9.51% (95/999), 28.09% (66/235) and 33.85% (130/384), respectively. The estimated annual incidence rate of JE was 0.12/100 000-0.79/100 000.ratio of cases 1.19∶1. Most of cases (27.30%) were children and adolescents aged 5-14 years and those (26.84%) aged over 45 year. Conclusion: The study found that primary and secondary school students are the key population of Nm meningitis, suggesting that it is necessary to explore the enhanced immunization study of meningococcal vaccine in this population; Sp has the possibility of occurrence in all age groups; <5 years old children are the main population of Hib meningitis.

Cost-effectiveness of the Haemophilus influenzae type b vaccine for infants in mainland China

ABSTRACTObjective: The aims of this study were to estimate the cost-effectiveness of the Haemophilus influenzae type b (Hib) vaccine for the prevention of childhood pneumonia, meningitis and other vaccine-preventable diseases in mainland China from a societal perspective and to provide information about the addition of the Hib vaccine to Chinese immunization programs.Methods: A decision tree and the Markov model were used to estimate the costs and effectiveness of the Hib vaccine versus no Hib vaccine for a birth cohort of 100,000 children in 2016. The disease burden was estimated from the literature, statistical yearbooks and field surveys. Vaccine costs were calculated from government reports and the United Nations International Children's Emergency Fund (UNICEF) website. The WHO cost-effectiveness thresholds were used to evaluate the Hib vaccine intervention. A one-way sensitivity analysis and probabilistic sensitivity analysis were performed to evaluate the parameter uncertainties.Results: Within the hypothetical cohort, under a vaccination coverage of 90%, the Hib vaccine could reduce 91.4% of Hib pneumonia and 88.3% of Hib meningitis; the Hib vaccine could also prevent 25 deaths, 24 meningitis sequelae cases and 9 hearing loss cases caused by Hib infection. From a societal perspective, the incremental cost-effectiveness ratio (ICER) of the Hib vaccine compared with no vaccination was US$ 13,640.1 at the market price, which was less than 3 times the GDP per capita of China in 2016. The ICER of the Hib vaccine was US$ −59,122.9 at the UNICEF price, indicating a cost savings. The largest portion of the uncertainty in the result was caused by the annual incidence of all-cause pneumonia, proportion of pneumonia caused by Hi, vaccine costs per dose, annual incidence of Hib meningitis and costs per episode of meningitis. The models were robust considering parameter uncertainties.Conclusion: The Hib vaccine is a cost-effective intervention among children in mainland China. The cost of Hib vaccine should be reduced, and it should be introduced into Chinese immunization programs.

Hospital-based Sentinel Surveillance of Haemophilus Influenzae Type B among Children in Burkina Faso, 2004-2012: Impact of Vaccine Introduction

Background: Haemophilus influenzae type b (Hib) is a leading cause of childhood bacterial meningitis in Africa. This study assessed the impact of Hib conjugate vaccine introduced in 2006 into the Expanded Program on Immunization (EPI) in Burkina Faso. Methods: From 2004-2012, we conducted hospital-based surveillance for invasive Hib disease among children <5 years of age with suspected bacterial meningitis. All cerebrospinal fluid (CSF) samples were tested using culture methods and/or PCR. Incidences calculated using population denominators were compared between pre-vaccine (2004-2005) and post- vaccine (2007-2012) periods. Results: 3928 cases of suspected meningitis were identified from the pediatric service, 231(5.9%) of whom had a bacterial pathogen confirmed. Hib was found in 80 (34.6%) of confirmed cases, followed by Streptococcus pneumoniae in 76 (32.90%) and Neisseria meningitidis in 54 (23.38%). The average annual incidence (per 1,00,000 children) of Hib meningitis was 4.11; the annual incidence of Hib meningitis declined by 94.13% from 16 per 1,00,000 in pre-vaccine (2004-2005) to 0.94 per 100 000 in post-vaccine (2007-2012) periods. None of the 80 Hib confirmed cases was immunized and no death was notified after the introduction of the vaccine. Conclusion: Admissions for Hib meningitis in the department of pediatrics at University Hospital, CHU-Yalgado Ouedraogo have practically disappeared two years after the introduction of the Hib vaccine into Burkina Faso’s Expanded Program on Immunization.

The Effectiveness of Conjugate Haemophilus influenzae Type B Vaccine in The Gambia 14 Years After Introduction

The Gambia was the first country in Africa to introduce conjugate Haemophilus influenzae type b (Hib) vaccine, which, as in other developing countries but unlike industrialized countries, is delivered as a 3-dose primary series with no booster. This study assessed its effectiveness 14 years after introduction. Using methods standardized during >20 years in the study site, clinical and microbiological surveillance for invasive Hib disease (primarily meningitis) in the Western Region of The Gambia from 2007 to 2010 was complemented with studies of Hib carriage in children aged 1 to <2 years, Hib antibody levels in children aged <5 years, and Hib vaccine coverage and timing in children aged 1 to <2 years. The incidence of Hib meningitis remained low (averaging 1.3 per 100 000 children aged <5 years annually), as did the Hib oropharyngeal carriage rate (0.9%). Hib antibody levels were protective in >99% of those surveyed, albeit with lower titers in older children; and coverage of conjugate Hib vaccination was high (91% having 3 doses at 1-2 years of age) using a schedule that was delivered at median ages of 2.6 months, 4.3 months, and 6 months for the first, second, and third doses, respectively. Conjugate Hib vaccine was delivered on time in a 3-dose primary series without booster to a high proportion of eligible children and this was associated with effective disease control up to 14 years after introduction. It is important that surveillance continues in this first African country to introduce the vaccine to determine if effective control persists or if a booster dose becomes necessary as has been the case in industrialized countries.

Impact of Introduction of the Haemophilus influenzae Type b Conjugate Vaccine into Childhood Immunization on Meningitis in Bangladeshi Infants

Some Asian countries have been reluctant to adopt Haemophilus influenzae type b (Hib) conjugate vaccination because of uncertainty over disease burden. We assessed the impact of introduction of Hib conjugate vaccine into the Expanded Program on Immunization in Bangladesh on purulent and laboratory-confirmed H influenzae meningitis. Within a well-defined catchment area around 2 surveillance hospitals in Dhaka, Bangladesh, we compared the incidence of Hib meningitis confirmed by culture, latex agglutination, and polymerase chain reaction assay among infants 1 year before and 1 year after introduction of Hib conjugate vaccine. We adjusted the incidence rate for the proportion of children who sought care at the surveillance hospitals. Among infants, the incidence of confirmed Hib meningitis decreased from 92-16 cases per 100,000 within 1 year of vaccine introduction (vaccine preventable incidence = 76; 95% CI 18, 135 per 100,000). The incidence of purulent meningitis decreased from 1659-1159 per 100,000 (vaccine preventable incidence = 500; 95% CI: 203, 799 per 100,000). During the same time period, there was no significant difference in the incidence of meningitis due to Streptococcus pneumoniae. Introduction of conjugate Hib conjugate vaccine into Bangladesh Expanded Program on Immunization markedly reduced the burden of Hib and purulent meningitis.

Cost-effectiveness of Haemophilus influenzae type b (Hib) vaccine introduction in the universal immunization schedule in Haryana State, India

In India, Haemophilus influenzae type b (Hib) vaccine introduction in the universal immunization programme requires evidence of its potential health impact and cost-effectiveness, as it is a costly vaccine. Since childhood mortality, vaccination coverage and health service utilization vary across states, the cost-effectiveness of introducing Hib vaccine was studied in Haryana state. A mathematical model was used to compare scenarios with and without Hib vaccination to estimate the cost-effectiveness of Hib vaccine in Haryana from 2010 to 2024. Demographic and National Family Health Surveys were used to estimate vaccination coverage and mortality rates among children under 5. Hib pneumonia, Hib meningitis and invasive Hib disease incidence were based on Indian studies. Vaccine and syringe prices of the UNICEF supply division were used. Cost-effectiveness from government and societal perspectives was calculated as the net incremental cost per unit of health benefit gained [disability-adjusted life years (DALYs) averted, life years saved, Hib cases averted, Hib deaths averted]. Sensitivity analysis was done using variation in parameter estimates among different states of India. The incremental cost of Hib vaccine introduction from a government and a societal perspective was estimated to be US$81.4 and US$27.5 million, respectively, from 2010 to 2024. Vaccination of 73.3, 71.6 and 67.4 million children with first, second and third dose of pentavalent vaccine, respectively, would avert 7 067 817 cases, 31 331 deaths and 994 564 DALYs. Incremental cost per DALY averted from a government (US$819) and a societal perspective (US$277) was found to be less than the per capita gross national income of India in 2009. In sensitivity analysis, Hib vaccine introduction remained cost-effective for India. Hib vaccine introduction is a cost-effective strategy in India.

Impact of vaccination against Haemophilus influenzae type b with and without a booster dose on meningitis in four South American countries

To inform World Health Organization recommendations regarding use of Haemophilus influenzae type b (Hib) vaccines in national immunization programs, a multi-country evaluation of trends in Hib meningitis incidence and prevalence of nasopharyngeal Hib carriage was conducted in four South American countries using either a primary, three-dose immunization schedule without a booster dose or with a booster dose in the second year of life. Surveillance data suggest that high coverage of Hib conjugate vaccine sustained low incidence of Hib meningitis and low prevalence of Hib carriage whether or not a booster dose was used.

Rapid assessment of Hib disease burden in Vietnam

BackgroundSeveral countries have applied the Haemophilus influenzae type b (Hib) rapid assessment tool (RAT) to estimate the burden of Hib disease where resources for hospital- or population-based surveillance are limited. In Vietnam, we used the Hib RAT to estimate the burden of Hib pneumonia and meningitis prior to Hib vaccine introduction.MethodsLaboratory, hospitalization and mortality data were collected for the period January 2004 through December 2005 from five representative hospitals. Based on the WHO Hib RAT protocol, standardized MS Excel spreadsheets were completed to generate meningitis and pneumonia case and death figures.ResultsWe found 35 to 77 Hib meningitis deaths and 441 to 957 Hib pneumonia deaths among children < 5 years of age annually in Vietnam. Overall, the incidence of Hib meningitis was estimated at 18/100,000 (95% confidence interval, CI, 15.1-21.6). The estimated Hib meningitis incidence in children < 5 years age was higher in Ho Chi Minh City (22.5/100,000 [95% CI, 18.4-27.5]) compared to Hanoi (9.8/100,000 [95% CI, 6.5-14.8]). The Hib RAT suggests that there are a total of 883 to 1,915 cases of Hib meningitis and 4,414 to 9,574 cases of Hib pneumonia per year in Vietnam.ConclusionsIn Hanoi, the estimated incidence of Hib meningitis for children < 5 years of age was similar to that described in previous population-based studies of Hib meningitis conducted from 1999 through 2002. Results from the Hib RAT suggest that there is a substantial, yet unmeasured, disease burden associated with Hib pneumonia in Vietnamese children.

Burden of Haemophilus influenzae type B disease in Pakistani children

Estimates of the burden of Haemophilus influenzae type b (Hib) in children in Pakistan are limited. A prospective surveillance was set up in 8 sentinel sites in Karachi and Hyderabad in January 2004. A total of 1481 children aged < 5 years underwent lumbar puncture for suspected acute bacterial meningitis. Specimens from 237 (16.0%) children met the criteria for probable bacterial meningitis, and Hib was detected in 45 of them (19.0%). The minimum detected incidence of Hib meningitis in the Hyderabad area was 7.6 per 100 000 in children < 5 years of age, and 38.1 per 100 000 children < 1 year. Hib vaccination is justified for inclusion in Pakistan's expanded programme of immunization.

The Elimination of Haemophilus influenzae type b Meningitis Following Conjugate Vaccine Introduction in Senegal

Senegal introduced routine infant Haemophilus influenzae type b (Hib) conjugate vaccine during 2005. We evaluated acute bacterial meningitis surveillance data among children 0 to 59 months of age collected during January 2003 to September 2007 at the major pediatric referral hospital in the Dakar Region of Senegal. Hib vaccine effectiveness was assessed using a case-control design. A total of 1749 children with suspected bacterial meningitis were included in the current study of whom 142 (8%) had Hib identified. Among children less than age 1 year, the average annual Hib meningitis incidence decreased from 22 to 47 per 100,000 during 2003-2005 to 1.4 per 100,000 during 2007, while pneumococcal meningitis incidence remained stable. Before vaccine introduction, calculated incidences varied over 4-fold between districts within the Dakar Region for the years 2003 to 2005. Following use of Hib vaccine, pneumococcus has now become the most common etiology of pediatric acute bacterial meningitis in Dakar region. Senegal successfully implemented Hib conjugate vaccine into their routine infant immunization program with a resultant near elimination of Hib meningitis burden.

Incidence of childhood Haemophilus influenzae type b meningitis in Sri Lanka

Objective To demonstrate the burden of Haemophilus influenzae type b (Hib) disease in Sri Lanka and provide information for decision-making in public health planning and vaccine introduction. Methods This was a prospective, population-based study carried out in 2004, to describe the epidemiology and calculate the incidence of meningitis caused by Hib in children <5 years of age in the district of Colombo, Sri Lanka. Hib was identified in cerebrospinal fluid (CSF) specimens by culture and antigen detection (latex agglutination test; LAT). Results The lumbar puncture rate in children <5 years of age was 1.9%. A causative bacterial organism was identified in 108 meningitis cases, and in 54 (50%) this was Hib. The LAT increased the Hib detection rate in CSF four-fold. In 2004, the annual incidence of Hib meningitis in Colombo was 20.1 cases per 100 000 children aged <5 years. Conclusions This study is the first from Sri Lanka reporting the Hib meningitis incidence rate pre-vaccine introduction. The reported incidence rate is one of the highest from the Asian region, but is likely an underestimation considering the difficulties in the laboratory identification of Hib.

Burden of disease caused by Haemophilus influenzae type b in children younger than 5 years: global estimates

Haemophilus influenzae type b (Hib) is a leading cause of childhood bacterial meningitis, pneumonia, and other serious infections. Hib disease can be almost completely eliminated through routine vaccination. We assessed the global burden of disease to help national policy makers and international donors set priorities. We did a comprehensive literature search of studies of Hib disease incidence, case-fatality ratios, age distribution, syndrome distribution, and effect of Hib vaccine. We used vaccine trial data to estimate the proportion of pneumonia cases and pneumonia deaths caused by Hib. We applied these proportions to WHO country-specific estimates of pneumonia cases and deaths to estimate Hib pneumonia burden. We used data from surveillance studies to develop estimates of incidence and mortality of Hib meningitis and serious non-pneumonia, non-meningitis disease. If available, high-quality data were used for national estimates of Hib meningitis and non-pneumonia, non-meningitis disease burden. Otherwise, estimates were based on data from other countries matched as closely as possible for geographic region and child mortality. Estimates were adjusted for HIV prevalence and access to care. Disease burden was estimated for the year 2000 in children younger than 5 years. We calculated that Hib caused about 8.13 million serious illnesses worldwide in 2000 (uncertainty range 7.33-13.2 million). We estimated that Hib caused 371,000 deaths (247,000-527,000) in children aged 1-59 months, of which 8100 (5600-10,000) were in HIV-positive and 363,000 (242,000-517,000) in HIV-negative children. Global burden of Hib disease is substantial and almost entirely vaccine preventable. Expanded use of Hib vaccine could reduce childhood pneumonia and meningitis, and decrease child mortality. GAVI Alliance and the Vaccine Fund.

Authors' Reply to "Is Hib Vaccine of Economic Value in South Korea?"

We appreciate Dr. Griffiths and colleagues' letter and their interest in our paper (1). They raised quite an important fundamental issue regarding the cost-benefit analysis (CBA) study. In CBA study, many assumptions are needed because of the lack of baseline data, which are the main weakness of this kind of study. We also did several assumptions, which are not verified in other studies. Dr. Griffiths et al. pointed out this. Therefore, the CBA study can be a reference in decision on health policy, especially when the policy on national immunization, but many other discussions are also very important. First, Dr. Griffiths et al. mentioned the unreasonably high price of the Hib vaccine in Korea in our study. It was one of most serious difficulties when gathering information regarding the vaccine price in the conduction of CBA. Thus far, the Hib vaccine has not been included in the Korean universal vaccination, and no data existed regarding the Hib vaccine. Therefore, we went through the vaccine prices in private clinics in 2003. The price of the Hib immunization is KRW 40,000, which includes the vaccine (around KRW27,000-30,000) and administration (around KRW10,000). Based on this data, it was assumed that there would be a 50% reduction in the administrative costs and a 20% reduction in the cost of the Hib vaccine. Therefore, we used KRW26,000 per shot. If the Hib immunization, however, was adopted in a national immunization schedule, the cost of the vaccine would probably be lower due to the economy of scale. Under another scenario, applying US$9 or US$11 per dose as in US, the benefit-cost ratio of Hib immunization in our paper (1) would be increased to 1.52-1.86, and then we could expect the economic efficiency to increase significantly. Second, Dr. Griffiths et al. pointed out the incidence data of Hib infection in this study. The study by Kim et al. (2), which was used to estimate the annual incidence in our study, was the first population-based study and the only report of annual incidence of Hib meningitis in Korea. However, this study did not include Hib infection apart from Hib meningitis. Unavoidably, we had to assume the incidence rate of Hib pneumonia based on United States' epidemiology data (3). To estimate Hib pneumonia in Korea, the proportion of meningitis and pneumonia in US was initially estimated, and the rate was then applied to estimate Korean Hib pneumonia incidence. In addition, the trend of Korean Hib meningitis is not equal to those of other Asian countries; therefore, it is also difficult to assume that Hib pneumonia is more prevalent than Hib meningitis, as in Indonesia. Although a sensitivity analysis was conducted to test uncertainty concerning the incidence of Hib infection, we also recognize that a problem of estimation of the incidence based on other country's epidemiologic data exists. We completely agree with Dr. Griffiths et al. last point. Economic evaluation is just one method available to provide information to help develop policy. Despite the low economic efficiency, we would like to point out that there are a significant number of cases of disease, deaths and sequelae that can be prevented by Hib vaccination. The scope of this study, however, was to test the efficiency of Hib universal immunization based on a CBA. Except for the CBA, other discussions regarding whether Hib vaccination should be included in the Korean national vaccination program are beyond the scope of this study; therefore, discussion on that point was not included.

Surveillance des méningites à Haemophilus Influenzae de l'enfant en France, 2001-2006

The implementation of Haemophilus influenzae b (Hib) vaccination program in France in 1993 resulted in a rapid and dramatic decrease of the Hib meningitis incidence in children. The aim of our study was to describe the residual Haemophilus influenzae (Hi) meningitis in the French paediatric population between 2001 and 2006. The French Paediatric Infectious Diseases Group set up an active surveillance network to analyze the clinical and biological features of bacterial meningitis. We used these data to retrospectively study the risk factors, signs and symptoms, vaccination status, cerebrospinal fluid analysis, treatment and case fatality rate of Hi meningitis. Among the 2539 cases of bacterial meningitis reported in France between 2001 and 2006, 69 (2.7 %) were due to Hi. A mean number of 11.5 cases of Hi meningitis was reported annually (minimum 6, maximum 16). Among Hi meningitis cases, 36 strains were of serotype b, 8 were capsulated but not b (6 f, 1 e and 1 unknown serotype), 20 strains were not capsulated, and 5 were non studied. The mean age of the children was 30.3 months (median 13.8 months, range 3.3 months to 14.5 years). 41 % of children with Hib meningitis did not received any anti-Hib vaccine and 41 % did not followed the French recommendations for Hib vaccine. Hi meningitis still occurs, and more than half is due to the b serotype. Among Hib cases, 14 % did not recieved any anti-Hib vaccine and 15 % received an incomplete vaccination schedule. Increase of vaccine coverage and use of an earlier booster dose at the age of 12 months could further improve the epidemiology of Hib meningitis. The immunity of children with Hib meningitis should be systematically studied in order to improve the comprehension of the pathophysiology of vaccine failure.

Action for child survival: elimination of Haemophilus influenzae type b meningitis in Uganda

To guide immunization policy, we determined the public health benefit of introducing Haemophilus influenzae type b (Hib) vaccine in Uganda and estimated the vaccine effectiveness. Surveillance data for acute bacterial meningitis among children aged 0-59 months were reviewed from three hospital sentinel sites, for July 2001 to June 2007, to determine the incidence of Hib meningitis, the effectiveness of Hib vaccine with a case-control design, and the number of vaccine-preventable cases and deaths of Hib disease in Uganda. Of the 13 978 children from 17 districts with suspected bacterial meningitis, 269 had confirmed Hib meningitis, declining from 69 patients in the prevaccine year (2001-2002) to three in 2006-2007. Hib meningitis incidence dropped from 88 cases per 100,000 children aged < 5 years in the year before vaccine introduction to 13 within 4 years, and to near zero in the fifth year. Vaccine effectiveness for 2 or more doses was 93% (95% confidence interval, CI: 69-99) against confirmed Hib meningitis and 53% (95% CI: 11-68) against purulent meningitis of unknown cause. In Uganda, Hib vaccine prevents an estimated 28 000 cases of pneumonia and meningitis, 5000 deaths and 1000 severe meningitis sequelae each year. Infant immunization with Hib vaccine has virtually eliminated Hib meningitis in Uganda within 5 years. Ensuring long-term benefits of Hib vaccine urgently requires sustainable vaccine financing, high-quality ongoing surveillance, and a health sector able to deliver a robust immunization programme.

Progress in vaccination against Haemophilus influenzae type b in the Americas.

Worldwide, Haemophilus influenzae type b (Hib) causes at least 3 million cases of severe disease each year. Approximately 400,000 children die annually due to pneumonia or meningitis caused by Hib [1]. Severe neurological sequelae occur in 15% to 30% of those who survive Hib meningitis [2]. Other, less frequent, manifestations of Hib are epiglottitis, septic arthritis, osteomyelitis, and septicemia [1–3]. Current polysaccharide–protein conjugate Hib vaccines are highly efficacious and safe. Primary series of two or three doses protect approximately 95% of infants [4–8]. Universal infant Hib immunization has proven to dramatically reduce Hib invasive disease [9–13] through direct vaccine protection and an important herd effect related to the reduction in Hib nasopharyngeal carriage in the community [12,14–16]. Adverse events are rare, and Hib vaccine is contraindicated only for persons with hypersensitivity to any of the vaccine's components [8,17]. The World Health Organization (WHO) recommends the introduction of Hib vaccines worldwide [1]. Furthermore, the Global Alliance for Vaccines and Immunization (GAVI Alliance)—an organization that aligns public and private resources in a global effort to create greater access to the benefits of immunization—considers Hib vaccine introduction in the world's poorest countries to be a top priority [18]. Prior to vaccine introduction, an estimated 20,000 cases of Hib meningitis were estimated to occur in countries of Latin America and the Caribbean (LAC) annually, based on an overall Hib meningitis incidence of 35 per 100,000 children aged 0–4 years [19]. Another 20,000 cases of invasive Hib disease were estimated to occur in the United States annually [20]. Most cases occurred in children aged less than 24 months, with at least 60% of cases occurring in children aged 0–11 months in half of the studies. The annual mortality rate for Hib meningitis in children aged less than five years was estimated to be around two per 100,000 in the Western Hemisphere [21]. Summary Points Hib vaccine introduction in countries of Latin America and the Caribbean has substantially reduced morbidity and mortality due to invasive Hib infections. All Latin American and Caribbean countries but one include Hib vaccine in their routine immunization schedule for infants. Factors that favored this region-wide Hib vaccine adoption include strong political will, data supporting Hib disease burden and impact in early adopting countries, and experience exchange among countries. Financial sustainability when introducing the more expensive Hib vaccine was critical for ensuring successful vaccine introduction in all countries. Efforts are still needed to improve vaccination coverage and to strengthen invasive bacterial disease surveillance in developing countries. In this article, we review the progress of vaccine introduction, lessons learned, and remaining challenges regarding Hib vaccination in the Americas, with emphasis on LAC countries. We expect that this updated and summarized information on Hib vaccination will serve as a useful reference to public health officials and policy makers from other regions who face the challenge of introducing Hib and other new or underutilized vaccines.

Vaccination policy and programs in the circumpolar world

In Canada the introduction of the Haemophilus influenzae type b (Hib) capsular polysaccharide-protein conjugate vaccines in 1988 led to a reduction in the annual incidence of Hib meningitis in children less than 5 years of age from approximately 44/100,000 in 1985 to &1/100,000 by 1994 (1). This reduction in morbidity and mortality was particularly dramatic among the Canadian Inuit, who had suffered the highest reported incidence of Hib meningitis (530/100,000 children less than 5 years) among indigenous populations worldwide (2).

Economic evaluation of delivering Haemophilus influenzae type b vaccine in routine immunization services in Kenya.

Haemophilus influenzae type b (Hib) vaccine was introduced into routine immunization services in Kenya in 2001. We aimed to estimate the cost-effectiveness of Hib vaccine delivery. A model was developed to follow the Kenyan 2004 birth cohort until death, with and without Hib vaccine. Incidence of invasive Hib disease was estimated at Kilifi District Hospital and in the surrounding demographic surveillance system in coastal Kenya. National Hib disease incidence was estimated by adjusting incidence observed by passive hospital surveillance using assumptions about access to care. Case fatality rates were also assumed dependent on access to care. A price of US$ 3.65 per dose of pentavalent diphtheria-tetanus-pertussis-hep B-Hib vaccine was used. Multivariate Monte Carlo simulations were performed in order to assess the impact on the cost-effectiveness ratios of uncertainty in parameter values. The introduction of Hib vaccine reduced the estimated incidence of Hib meningitis per 100,000 children aged < 5 years from 71 to 8; of Hib non-meningitic invasive disease from 61 to 7; and of non-bacteraemic Hib pneumonia from 296 to 34. The costs per discounted disability adjusted life year (DALY) and per discounted death averted were US$ 38 (95% confidence interval, CI: 26-63) and US$ 1197 (95% CI: 814-2021) respectively. Most of the uncertainty in the results was due to uncertain access to care parameters. The break-even pentavalent vaccine price--where incremental Hib vaccination costs equal treatment costs averted from Hib disease--was US$ 1.82 per dose. Hib vaccine is a highly cost-effective intervention in Kenya. It would be cost-saving if the vaccine price was below half of its present level.