Abstract and Introduction
Abstract
New Zealand (Aotearoa) experienced a Neisseria meningitidis serogroup B epidemic during 1991–2006, and incidence remains twice that of other high-income countries. We reviewed clinical, laboratory, and immunization data for children <15 years of age with laboratory-confirmed invasive meningococcal disease in Auckland, New Zealand, during January 1, 2004–December 31, 2020. Of 319 cases in 318 children, 4.1% died, and 23.6% with follow-up data experienced sequelae. Children of Māori and Pacific ethnicity and those living in the most deprived areas were overrepresented. Eighty-one percent were positive for N. meningitidis serogroup B, 8.6% for serogroup W, 6.3% for serogroup C, and 3.7% for serogroup Y. Seventy-nine percent had bacteremia, and 63.9% had meningitis. In New Zealand, Māori and Pacific children are disproportionately affected by this preventable disease. N. meningitidis serogroup B vaccine should be included in the New Zealand National Immunization Schedule to address this persistent health
inequity.
Introduction
Invasive meningococcal disease (IMD) is a bacterial infection with typically rapid onset. In children, infection is associated with high (7%–9%) case-fatality rates (CFRs) and serious long-term sequelae[1,2]. Infants and young children have the highest incidence of disease; a second peak occurs during adolescence[3]. IMD inequitably affects Indigenous populations and persons living in areas of deprivation[3,4].
The bacterium Neisseria meningitidis is categorized into serogroups based on its polysaccharide capsule; 6 serogroups (A, B, C, W, X, and Y) are responsible for
nearly all IMD cases worldwide[5]. The major clinical manifestations of IMD are meningitis and sepsis. Early recognition is critical because sepsis can rapidly
progress to multiorgan dysfunction and death[6]. A leading cause of admission to pediatric intensive care units (ICUs) throughout Australasia[7], IMD can lead to disabling, long-term sequelae for approximately one third of surviving children, including hearing loss,
neurodevelopmental impairment, limb or digit loss, and scarring[2,8,9]. Those sequelae heavily affect healthcare resources and the quality of life of affected children and their families[2,9].
Epidemiology of IMD Globally and in New Zealand
The global incidence of IMD has declined over the past 20 years, partly because of the availability of safe, effective vaccines
for all major disease-causing serogroups and successful vaccination programs[5]. Overall incidence of IMD in most high-income countries is well under 1.5 per 100,000 per year[5]. In contrast, New Zealand (Aotearoa) reports the highest rate of N. meningitidis serogroup B (MenB) disease in the world[3,5,10]. During 1991–2006, New Zealand experienced a prolonged MenB epidemic caused by the B:P1.7–2,4 strain[11]. The epidemic peaked in 2001, with an incidence of 17.4 cases/100,000 persons in the overall population and 212 cases/100,000
infants[11]. In response, MeNZB, a strain-specific outer membrane vesicle (OMV) vaccine, was developed and delivered nationally in 3 doses to persons <20 years of age during 2004–2006 and in 4 doses to infants during 2006–2008[11]. Overall vaccination coverage was 80%, and coverage was higher among Pacific peoples compared with those of other ethnicities. The vaccine effectiveness of MeNZB against the epidemic strain was estimated at 68%–77% and was associated with the waning of the epidemic[4,11].
Since that time, regional outbreaks of N. meningitidis serogroup C (MenC) and serogroup W (MenW) disease have been associated with high CFRs, prompting emergency targeted vaccination
programs in 2011 and 2018[12,13]. However, since 2014, the incidence of IMD in NZ has been increasing, up to an overall rate of 2.8 cases/100,000 persons
in 2019[3]. Almost half of cases in 2019 occurred in children <15 years of age, and the highest rates in infants <1 year of age (51.5/100,000 infants). As observed internationally, an increasing proportion of IMD caused by MenW has occurred in New Zealand, accounting for 30% of the country’s cases in 2019[3,5]. Auckland, New Zealand’s largest city, has a pediatric (<15 years of age) population of ≈320,000, which makes up 34% of the total New Zealand pediatric population[14]. Ethnic groups in Auckland include Māori (18%), Pacific peoples (19%), and those of Asian (25%) and European (34%) heritage.
Meningococcal Vaccines
A 4-component MenB vaccine, 4CMenB (Bexsero; GlaxoSmithKline), was developed using 3 subcapsular antigens and the NZ MeNZB
OMV vaccine[15]. Vaccine effectiveness data from Australia, Canada, Italy, and the United Kingdom show reductions in MenB of 71%–100% in eligible cohorts 2–5 years after 4CMenB was introduced[15]. Although there is no evidence that 4CMenB reduces N. meningitidis carriage[16], OMV meningococcal vaccines appear to provide some protection against IMD caused by non-MenB serogroups, as well as against
N. gonorrhoeae[17,18]. Although 4CMenB and MenACWY vaccines are funded in New Zealand for a small number of persons with high-risk medical conditions and, recently, for adolescents in certain collective residences, no meningococcal vaccines are universally funded in the National Immunization Schedule. We aimed to describe the experience of pediatric IMD in Auckland during 2004–2020—including demographic factors; clinical, microbiological, and laboratory features; treatment; and outcomes—to demonstrate the impact of IMD on children in New Zealand and to highlight the need for funding of meningococcal vaccines.