From secondary prevention to primary prevention: a unique strategy that gives hope to a country ravaged by meningococcal disease
Introduction
Since 1991, New Zealand has been in the middle of an epidemic caused by a single strain of group B meningococcal disease dominated by a strain defined as, B:4:P1.7b,4 [1]. Meningococcal disease can result in significant personal costs to those afflicted with the disease, given approximately 11–19% of cases never fully recover and suffer ongoing long-term disability [2]. It is also a disease that affects the wider community with a significant fear of the sequelae and death.
In a population of 4 million people, over 5550 cases and 222 deaths have occurred in the current epidemic. However, the burden of disease has not been equally spread with children of indigenous Maori and Pacific ethnicity faced with high rates of meningococcal disease for a developed country, particularly those under 1 year of age. Based on aggregated data 1997–2003, a Pacific child has a 1 in 68 chance of contracting the disease by the time they turn 5 years. For a Maori child, this risk is 1/117 and European or other peoples 1/438.
Since 1995, New Zealand has actively managed meningococcal disease through secondary prevention measures, including intensified epidemiological surveillance, promoting public awareness to encourage early medical intervention, promoting professional awareness to encourage early diagnosis and treatment, and prevention of secondary cases by notification, contact tracing and offering prophylactic antibiotics. A 3-year case control risk study was also undertaken to identify modifiable risk factors [3].
The search for a safe and effective serogroup B meningococcal vaccine was also part of the national strategy. The Meningococcal Vaccine Strategy (MVS) offers a primary prevention intervention against a disease that has negatively impacted many New Zealand communities for too long. There is now an opportunity to control the current epidemic with the licensure of the MeNZB™ vaccine and the commencement of the Meningococcal B Immunisation Programme. The delivery of the vaccine is designed to focus attention, effort and resources on reaching those most at risk, with the view to improving health outcomes. Its goal is to achieve this aim within 2 years by immunising 90% of the population aged 6 weeks to 19 years inclusive.
A cost–utility study undertaken by the University of Auckland supported the Government approach of funding a nationwide group B Meningococcal Immunisation Programme. The economic results demonstrated that, from a societal perspective, immunisation against meningococcal disease is likely to be highly cost-effective and moderately cost-effective from a governmental perspective. The cost-effectiveness of immunisation would be higher for Maori and Pacific than for people of other ethnicities, and in regions where the incidence of meningococcal disease is high. The existing and ongoing societal costs of meningococcal disease have been estimated at US$ 970 million,2 of which, the direct costs to the New Zealand health sector is US$ 460 million [4]. The US$ 460 million figure includes ongoing treatment and rehabilitative costs, but does not include the human costs associated with death, or the loss of quality of life from the long-term disability of the disease.
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Epidemiology
Although the incidence of meningococcal disease is high, New Zealand's case-fatality rate (CFR) is low. International literature reports case-fatality rates in European countries of between 3.5 and 20.5% in 2002 [5]. By comparison, meningococcal disease in New Zealand resulted in 13 deaths in 2003, a rate of 2.4%, the lowest to date in the New Zealand epidemic [6].
The New Zealand group B epidemic had an incidence rate of approximately 13–18 per 100,000 population for the past 8 years. The
Group B meningococcal vaccines
Vaccines not targeting group B meningococci have been produced using the capsular polysaccharides. The development of a safe and effective vaccine that protects against serogroup B meningococcal disease is complex because of poor immunogenicity of the group B polysaccharide capsule. This has meant that the development of serogroup B meningococcal vaccines has focused on subcapsular outer-membrane antigens that are mostly strain-specific [7].
The use of the outer-membrane vesicle (OMV) group B
Strain-specific OMV vaccine for New Zealand
In 1998, the World Health Organization (WHO) was approached for advice on vaccine manufacturers, who may be interested and able to assist New Zealand. A meeting of manufacturers, international and New Zealand advisors, and the Ministry of Health was held in Geneva under the auspices of the WHO in September 1998 and proposed a way forward. The WHO established an International Advisory Group of experts to assist New Zealand. The WHO continued to offer advice to resolve technical and commercial
New Zealand strategy
The New Zealand strategy to control the strain specific epidemic of meningococcal disease in New Zealand by immunisation is built on five components. These are:
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development of a safe and immunogenic tailor-made vaccine;
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a validated assay;
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licensure using provisional consent;
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intensive post-licensure safety surveillance monitoring;
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careful assessment of vaccine effectiveness.
New Zealand's approach, involving the collaborative efforts of a government agency, vaccine company, university and laboratory
New Zealand health sector structure
The New Zealand Ministry of Health has spent over 3 years working with the health sector to establish a national framework for delivery of the programme to ensure coverage targets are reached. The delivery of the immunisation programme is being managed, planned and delivered locally by District Health Boards (DHBs). Since 2000, 21 DHBs were established to plan, fund, and provide health services for defined populations in New Zealand. A DHB assesses the needs of their resident population, and
Meningococcal B Immunisation Programme
The Meningococcal B Immunisation Programme is an important means of reducing the health inequalities for Maori and Pacific children and children living in poor socio-economic environments. For the immunisation programme to be successful, it is important that Maori and Pacific children receive the full three-dose course of the MeNZB™ vaccine.
Both Maori and Pacific peoples have a strong association with their extended family and wider community. To be effective in targeting and reaching both
Effective delivery strategies
The delivery of the MeNZB™ vaccine is designed to focus attention, effort and resources on reaching those most at risk, with the view to improving health outcomes. The delivery models operated by each DHB reflect the devolved healthcare system and increased level of community engagement in development of local strategies to reach high-risk populations.
The first stage of the nationwide programme has begun in Counties-Manukau DHB in south Auckland and the eastern suburbs of Auckland DHB. The
Conclusion
The collaborative efforts of a government agency, vaccine company, university and laboratory institute, have allowed the development of the Meningococcal Vaccine Strategy that have supported the rapid introduction in New Zealand of a strain specific serogroup B OMV vaccine. The delivery of the MeNZB™ vaccine will be New Zealand's largest immunisation programme with three doses given at six-week intervals to over 1 million children and youth aged between 6 weeks and 19 years inclusive.
Acknowledgements
Stuart Parkinson, Gabrielle Roberts, Christine Roseveare and Ann Shaw (Ministry of Health, New Zealand).
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