Hib Initiative Research & Surveillance ActivitiesPriorities of the Hib Initiative in the field of research and surveillance include the development and assessment of novel methods to demonstrate Hib disease burden and vaccine impact. The Hib Initiative has identified three strategic geographic regions, and within each region activities are developed according to the needs of individual countries. In addition, activities are planned and conducted globally especially in the area of global coordination and research. Recently, the Hib Initiative approved a series of solicited and unsolicited proposals to fund research studies in 16 GAVI-eligible countries to a sum of approximately $6 million. In a continued effort to encourage adoption of Hib vaccine and sustained use, these studies will assess the impact and cost effectiveness of the vaccine, strengthen surveillance, and examine long term sequelae of invasive Hib disease. Additional information on these studies will be provided here as soon as they become available. For a description of regional and country-specific research and surveillance activities, please select a region from the map:
Disease Burden MeasurementDisease burden measurement is an integral component in making evidence informed decisions. This can be accomplished through a number of methods including:
Vaccine Probe StudiesThe challenges of surveillance studies have led investigators to undertake studies using Hib conjugate vaccine as a ‘probe’ to identify reductions in disease burden. This is measured by determining the proportion of pneumonia and meningitis cases prevented during clinical trials of Hib conjugate vaccine. Three studies have used this method including, The Gambia, Chile, and Indonesia. In the Gambia approximately 21% of hospitalized pneumonia cases with radiographic infiltrates were prevented by Hib conjugate vaccine. In Chile a case-control trial concluded that approximately 23% of hospitalized pneumonia cases with radiographic consolidation were prevented by Hib vaccine. The randomized clinical trial conducted in Lombok found a moderate incidence of culture confirmed Hib disease. The vaccine prevented approximately 10 times as many cases of clinical, non-culture confirmed meningitis than culture confirmed cases – suggesting the annual incidence of Hib Meningitis is 158/100,000 children under the age of 2 years. For more information see abstract and slides below. Other Relevant studies: Impact StudiesImpact studies can be used to measure the differences in disease between vaccinated and unvaccinated groups. Hib vaccine impact studies can be designed to estimate the impact on laboratory confirmed Hib disease, purulent meningitis and x-ray confirmed pneumonia. Pneumonia studiesIt has been 8 years since the Gambia probe study [Mulholland, Lancet, 1997] used radiology to provide the first solid evidence of the effectiveness of Hib vaccination in reducing childhood pneumonia. After the trial in The Gambia, a retrospective cohort study in Chile and case-control studies in Brazil, Bangladesh, and Colombia, also confirmed the impact of Hib vaccination on pneumonia defined by radiology. However, a vaccine probe study in Lombok, Indonesia found no impact on x-ray confirmed pneumonia, despite a measurable impact on all clinical pneumonia. For a summary of eight randomized trials that compared the efficacy of H. influenzae type b conjugate vaccine to placebo or no vaccine see: Efficacy of Haemophilus influenzae type b vaccination of children: a meta-analysis Meningitis/Invasive Hib Disease StudiesThere have been a number of important articles that have highlighted the reduction of invasive Hib disease through routine Hib vaccination. In Kenya, the introduction of Hib vaccine reduced invasive Hib disease rates by 88%. Studies in Malawi and South Africa also demonstrated a reduction of invasive Hib disease. See abstracts below.
Comprehensive literature searches on meningitis studies were conducted by WHO. The results are summarized in Vaccines and Biologicals by region. HIV Infected Populations The studies from Malawi and South Africa also present data on the efficacy of the vaccine in HIV populations. In Malawi, researchers determined the Hib conjugate vaccine to be highly effective in reducing Hib meningitis cases even in HIV infected children. Vaccine effectiveness in preventing Hib meningitis among HIV positive children with 2 or more doses adjusting for age and residence was 100%. Before vaccine introduction, on average 10 children per year has Hib meningitis and were HIV positive compared to zero in 2005. In South Africa the Hib conjugate vaccine was less effective among HIV–1 infected children although it was 83% effective in preventing overall invasive Hib diseases. Population based surveillanceAlthough Hib vaccines have been proven to be safe and effective, developing countries have been slow to introduce. The following population based surveillance protocol will allow for the estimation of local burden of bacterial meningitis and assist managers who are considering Hib conjugate vaccine introduction. This protocol requires
There are several studies that have used this protocol:
For more information, view 'Generic protocol for population-based surveillance of Haemophilus influenzae type B'. Hib Rapid AssessmentThe Hib RAT is a tool used to estimate the local burden of Haemophilus influenzae type b where population based surveillance as described above has not been established. Many countries have utilized this tool
For more information, view 'Estimating the local burden of Haemophilus influenzae type b (Hib) disease preventable by vaccination' (PDF). Sentinel Site SurveillanceThe following manual provides guidelines to establish sentinel surveillance for Haemophilus influenzae type B and other childhood bacterial meningitis to provide data on the burden of Hib meningitis in children and to determine the impact of Hib vaccination programs. Hib-Paediatric Bacterial Meningitis (Hib-PBM) Surveillance Network (PDF). For a description of this network view the WHO Communicable Diseases Epidemiological Report (July 2003) (PDF) or their website. Other WHO regions are in the process of (EURO) or have (EMRO, PAHO) established regional bacterial meningitis sentinel surveillance networks Laboratory Sentinel Surveillance for HibLaboratory confirmation of bacterial meningitis is relatively straightforward but only in hospital settings where the quality of clinical and laboratory practices is adequately controlled. Haemophilus influenzae is one of the more fastidious bacterial pathogens met in the clinical microbiology laboratory. It requires, amongst other things, X and V factor supplements and a 5-10% carbon dioxide enriched environment to grow. Other key factors limiting the successful isolation of Hib are: prior treatment of patients with antibiotics, delayed transport of CSF to the laboratory and poor internal quality control of laboratory practices, including the proper preparation and storage of the appropriate media culture plates. In most countries in Africa, suitable public hospital settings are found only in the major cities. However, since Haemophilus influenzae is an endemic disease, a well functioning sentinel based surveillance system is adequate to give an overall picture of the disease burden. For more information see the following articles and websites
For more information on other Studies click here: Studies on Sequelae
Resources
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Hib Rapid Assessments Worldwide