1950—2020年江苏省流行性脑脊髓膜炎流行特征及菌群变迁趋势分析

目的 分析江苏省1950—2020年流行性脑脊髓膜炎(流脑)流行发病趋势及菌群分布特征。方法 收集1950—2020年江苏省流脑病例监测数据,并对各时期流脑发病特征进行描述分析。结果 1950—2020年江苏省流脑报告病例1 067 148例,在1965年、1959年、1977年,经历了3次流行高峰,广泛使用疫苗后,流脑发病率下降明显,2006年以来,流脑发病率一直处在0.1/10万以下。2006—2010年,流脑病例C群比例为50.77%,A群为32.31%,B群为1.54%。2011—2015年,C群占33.33%,A群占20.00%,W135群占20.00%,B群占6.67%,其他及不可分群占比15.38%,2016—2020年,C群进一步减少为16.67%,A群减少至8.33%,B群比例增加至25.00%,W135群比例为16.67%,其他及不可分群上升为33.33%。结论 江苏省流脑疫情维持在低位,菌群由以C群为主,向B群为主变迁,其他及不可分群比例显著上升。流脑防控局面发生新变化。     

Changing epidemiology of Infant Meningococcal Disease after the introduction of meningococcal serogroup C vaccine in Italy, 2006–2014

BackgroundIn Italy, the incidence of Invasive Meningococcal Disease (IMD) was around 0.28 per 100,000 over the last years. Since the risk IMD is usually high among infants aged less than 1 year, we decided to evaluate the trend of IMD cases reported between 2006 and 2014 in this age group. In particular, the study aim was to describe the main characteristics of IMD cases in infants following the introduction of MCC vaccine (2005) and to estimate the number of cases which are potentially preventable through early vaccination.MethodsThe National Surveillance System of Bacterial Meningitis was established in 1994 and in 2007 was extended to all invasive bacterial diseases. Clinical data and isolates and/or clinical samples are collected from hospitalized patients throughout the country. IMD cases are reported by clinicians to the local health authorities, and samples are sent to the Reference Laboratory at the Istituto Superiore di Sanità for further characterization and storage at −80 °C. In particular, serogroup identification is obtained by agglutination with commercial antisera or by multiplex PCR.ResultsThe annual incidence for infants <1 year old remained rather stable of 3.6 per 100,000, with several upward and downward oscillations and a peak in 2010. The incidence of IMD among infants was more than 10 times higher than the overall rate of IMD observed in Italy. Finally, serogroup B was more frequently detected among infants aged <1 year, accounting for 65% of the total (p < 0.01).ConclusionsDuring the study period, IMD incidence reported among infants aged less than one year old was 10 times higher than the overall rate, and serogroup B was the most commonly detected over time. The long-term impact of meningococcal C conjugate vaccine and the effect of the introduction of meningococcal B vaccination among infants need to be evaluated.     

Meningococcal disease in South Africa, 1999-2002

We describe the epidemiology of invasive meningococcal disease in South Africa from August 1999 through July 2002, as reported to a laboratory-based surveillance system. Neisseria meningitidis isolates were further characterized. In total, 854 cases of laboratory-confirmed disease were reported, with an annual incidence rate of 0.64/100,000 population. Incidence was highest in infants < 1 year of age. Serogroup B caused 41% of cases; serogroup A, 23%; serogroup Y, 21%; serogroup C, 8%; and serogroup W135, 5%. Serogroup B was the predominant serogroup in Western Cape Province, and disease rates remained stable. Serogroup A was most prevalent in Gauteng Province and increased over the 3 years. On pulsed-field gel electrophoresis analysis, serogroup A strains showed clonality, and serogroup B demonstrated considerable diversity. Selected isolates of serogroup A belonged to sequence type (ST)-1 (subgroup I/II) complex, serogroup B to ST-32/electrophoretic type (ET)-5 complex, and serogroup W135 to ST-11/ET-37 complex.     

Impact of vaccination during an epidemic of serogroup C meningococcal disease in Salvador, Brazil

To combat rising incidence of serogroup C meningococcal disease in the city of Salvador, Brazil, the Bahia state immunization program initiated routine childhood immunization with meningococcal C conjugate vaccine (MenC) in February 2010, followed by mass MenC vaccination of city residents 10-24 years of age from May through August 2010. We analyzed trends in incidence of reported cases of meningococcal disease and serogroup distribution among meningococcal isolates identified in hospital-based surveillance in Salvador from January 2000 to December 2011 and estimated vaccine effectiveness using the screening method. Annual incidence of serogroup C meningococcal disease increased from 0.1 cases per 100,000 population during 2000-2006 to 2.3 in 2009 and 4.1 in 2010, before falling to 2.0 per 100,000 in 2011. Estimated coverage of mass vaccination reached 80%, 67% and 41% among 10-14, 15-19 and 20-24 year olds, respectively. Incidence in 2011 was significantly lower than average rates in 2008-2009 among children <5 years, but reductions among 10-24 year olds were not significant. Among 10-24 year olds, a single dose of MenC vaccine was 100% effective (95% confidence interval, 79-100%) against serogroup C meningococcal disease. Low coverage in the population targeted for mass vaccination may have limited impact on ongoing transmission of serogroup C meningococcal disease despite high vaccine effectiveness.     

Serogroup A,C, W,and Y meningococcal disease in persons previously vaccinated with a serogroup ACWY meningococcal vaccine – United States, 2014–2018

BackgroundThe Advisory Committee on Immunization Practices (ACIP) recommends routine vaccination with a quadrivalent meningococcal conjugate serogroup A,C,W,Y (MenACWY) vaccine at 11–12 years of age, with a booster dose at 16 years. ACIP also recommends meningococcal vaccination for persons at increased risk of meningococcal disease, including a 2-dose primary series and regular booster doses for persons at increased risk because of underlying medical conditions. U.S. cases of serogroup A, C, W, and Y meningococcal disease in persons previously vaccinated with MenACWY vaccine have not been systematically described since 2008. Characterization of these cases is important to understand potential factors leading to breakthrough disease.MethodsWe analyzed cases of serogroup A,C,W, and Y meningococcal disease reported through the National Notifiable Diseases Surveillance System (NNDSS) from 2014 through 2018. State health departments submitted additional information on risk factors and clinical course.ResultsDuring 2014–2018, 822 cases of serogroup A, C, W, and Y meningococcal disease were reported through NNDSS; 34 (4%) were in patients who previously received ≥ 1 dose of MenACWY vaccine. Twenty-three vaccinated patients were up-to-date on MenACWY vaccine per recommendations, and seven were not up-to-date; four were missing information on the number of doses received. Seventeen cases (50%) occurred > 3 years after the most recent dose. A significantly higher proportion of vaccinated patients were people living with HIV (PLWH) compared to unvaccinated patients. Eight of the 34 vaccinated patients were immunosuppressed, including five PLWH, one taking eculizumab, and two taking other immunosuppressive medications. The case fatality ratio did not differ between vaccinated and unvaccinated patients.ConclusionsImmunosuppression, incomplete vaccination, and waning immunity likely contributed to breakthrough cases of meningococcal disease among people who received MenACWY vaccine. Continued monitoring of serogroup A, C, W, and Y meningococcal disease in previously vaccinated persons will help inform meningococcal disease prevention efforts.     

Australian Meningococcal Surveillance Programme annual report, 2010

In 2010 there were 214 laboratory-confirmed cases of invasive meningococcal disease analysed by the National Neisseria Network, a nationwide network of reference laboratories. One hundred and twenty-four isolates of Neisseria meningitidis from invasive cases of meningococcal disease were available for which the phenotypes (serogroup, serotype and serosubtype) and/or genotype and antibiotic susceptibility were determined. An additional 90 cases were confirmed by non-culture based methods (77 by nucleic acid amplification testing and 13 by serology), and where possible, serotyping was determined. Nationally 167 (78%) laboratory-confirmed cases, where a serogroup was determined, were infected with serogroup B, 16 (7.5%) with serogroup C, 9 (4.2%) with serogroup W135 and 7 (3.3%) with serogroup Y meningococci. The national total of confirmed cases has decreased since 2004, but the number of cases may vary between jurisdictions each year. New South Wales had the highest number of recorded cases in 2010. Typical primary and secondary disease peaks were observed in those aged 4 years or less and in adolescents and young adults respectively. Serogroup B cases predominated in all age groups and jurisdictions. The common phenotype circulating in Australia continues to be B:15:P1.7, corresponding to the porA genotype P1.7,16-26. Serogroup C cases were again numerically low, as were serogroups W135 and Y. Eighty per cent of all isolates showed decreased susceptibility to the penicillin group of antibiotics (minimal inhibitory concentration (MIC) 0.06-0.5 mg/L). All isolates remained susceptible to ceftriaxone. One isolate had reduced susceptibility to ciprofloxacin, and none to rifampicin.     

Invasive meningococcal disease in Chile seven years after ACWY conjugate vaccine introduction

BackgroundA serogroup W (MenW) outbreak in Chile prompted a meningococcal vaccination campaign using tetravalent meningococcal-conjugate vaccines (MCV–ACWY) in children since 2012, followed by its introduction into the National Immunization Program (NIP) in toddlers from 2014. Direct protection was observed, but no indirect effects in other age-groups were evidenced. The aim of this study was to describe invasive meningococcal disease (IMD) cases in Chile between 2009 and 2019, and its trend after the introduction of MCV–ACWYs.MethodsIMD cases, cumulative incidence per 100,000 inhabitants, CFR, and vaccination uptake were described. Data were obtained from the Public Health Institute and NIP.ResultsOverall-IMD cases increased in 2009–2014 period, followed by a decline in 2015–2019, focused in infants, children <5 years and people ≥60 years. Serogroup B (MenB) and MenW alternate its predominance. Median overall incidence was 0.6/100,000, increasing from 0.6/100,000 in 2009 to 0.8/100,000 in 2014, later decreasing to 0.4/100,000 in 2019. Median incidences for MenB, serogroup C (MenC) and Y (MenY) were 0.25/100,000, <0.01/100,000 and <0.01/100,000, respectively. Median MenW incidence was 0.53/100,000, increasing from 0.01/100,000 in 2009 to 0.56/100,000 in 2014, followed by a constant decline to 0.12 in 2019. Infants, children <5 years and adults ≥60 years were affected the most, with median incidences of 9.7, 0.9 and 0.93, decreasing to 1.3, 0.1 and 0.1/100,000 in 2019, respectively. Median overall-CFR was 19%, 7.5% for MenB and 24.5% for MenW. Median MCV–ACWY uptake was 93%ConclusionOverall-IMD, MenW cases and incidence declined since 2015 after the MCV-ACWY introduction, while MenB, MenC and MenY have been stable. MenW incidence declined in all age groups, including non-immunized infants and people >60 years. Further analysis and a longer period of observation are needed to have a more robust conclusion about this epidemiological trend. By 2019, CFR remains high.     

An outbreak of serogroup C meningococcal disease in the province of Antwerp (Belgium) in 2001–2002

In 2001 an outbreak of Neisseria menigitidis serogroup C occurred in the province of Antwerp (Belgium). Over a year the incidence rate of meningococcal disease (MD) increased from 3.9 per 100,000 to 9.1 per 100,000 with a shift from serogroup B (87%) in 2000 to serogroup C (66%) in 2001. The most prominent phenotype was C:2a:P1.2,5. The incidence rate for serogroup C MD increased from 0.4 per 100,000 to 4.5 per 100,000 in 2001. The case fatality rate was 6.7% in 2001. After the introduction of a mass vaccination campaign with a conjugated vaccine against serogroup C MD the incidence of serogroup C MD fell from 4.5 to 1.8 per 100,000. As a result of the analysis of this outbreak, it was proposed to offer a vaccine against serogroup C to all people under 19 years of age. Part of this plan has been implemented to date in Belgium.     

Serogroup W-135 meningococcal disease during the Hajj, 2000

An outbreak of serogroup W-135 meningococcal disease occurred during the 2000 Hajj in Saudi Arabia. Disease was reported worldwide in Hajj pilgrims and their close contacts; however, most cases were identified in Saudi Arabia. Trends in Saudi meningococcal disease were evaluated and the epidemiology of Saudi cases from this outbreak described. Saudi national meningococcal disease incidence data for 1990 to 2000 were reviewed; cases from January 24 to June 5, 2000, were retrospectively reviewed. The 2000 Hajj outbreak consisted of distinct serogroup A and serogroup W-135 outbreaks. Of 253 identified cases in Saudi Arabia, 161 (64%) had serogroup identification; serogroups W-135 and A caused 93 (37%) and 60 (24%) cases with attack rates of 9 and 6 cases per 100,000 population, respectively. The 2000 Hajj outbreak was the first large serogroup W-135 meningococcal disease outbreak identified worldwide. Enhanced surveillance for serogroup W-135, especially in Africa, is essential to control this emerging epidemic disease.     

湖南省C群及W135群脑膜炎奈瑟菌的流行病学及病原学特征分型

目的了解湖南省C群和W135群脑膜炎奈瑟菌的流行病学及病原学特征。方法收集2006—2016年湖南省流行性脑脊髓膜炎患者的血液或脑脊液、患者密切接触者以及健康人群的咽拭子标本中分离到的脑膜炎奈瑟菌菌株,进行生化检测、血清学分群。选取其中的C群和W135群部分菌株进行药敏试验,并采用脉冲场凝胶电泳(PFGE)分型以及多位点序列分型(MLST)方法对菌株进行分子分型,分析其流行病学特征。结果经生化和血清学确认后,选取22株C群脑膜炎奈瑟菌和9株W135群脑膜炎奈瑟菌进行药敏试验,结果显示对大部分检测抗菌药物全部敏感,但对复方磺胺甲口恶唑C群菌株全部耐药,而W135群菌株的耐药率为55.56%,两者比较差异有统计学意义(χ~2=7.61,P=0.006)。经PFGE分型后,22株C群脑膜炎奈瑟菌共分为5种PFGE带型,其中5株HNC-01带型和13株HNC-02带型属同一亚型;2006年湖南省第1例C群患者分离菌株的PFGE带型为HNC-02,与2012、2013年患者以及患者密切接触者分离菌株的图谱完全一致,与带型为HNC-01的2008、2010、2013年的患者分离菌株仅有一个带型的差异,均属于优势带型。9株W135群脑膜炎奈瑟菌PFGE分型后共分为2个带型,其中首例患者与2013、2016年患者分离菌株的带型一致,均为HNW-01型。选取其中优势带型菌株经MLST后,结果 C群脑膜炎奈瑟菌为ST4821型,W135群脑膜炎奈瑟菌为ST11型,均属于脑膜炎奈瑟菌的高致病性克隆群。结论湖南省C群流脑和W135群流脑自首例病例出现后,各自都成为了该群病例的优势流行克隆群,C群流脑近年有减少态势,但出现了新的流行型别;W135群自2012年起成为我省新的流脑流行株,其优势菌株与国际上侵袭性的W群分型一致,可能引起新的大流行,应及时制定相应的防控政策。     

Hospital-based surveillance of meningococcal meningitis in Salvador, Brazil

This study aimed to describe the clinical, epidemiological and microbiological features of meningococcal meningitis in Salvador, Brazil. Between February 1996 and January 2001, a hospital-based surveillance prospectively identified cases of culture-positive meningococcal meningitis. Demographic and clinical data were collected through interview and medical chart review. Antisera and monoclonal antibodies were used to determine the serogroup and serotype:serosubtype of the isolates, respectively. Surveillance identified a total of 408 cases of meningococcal meningitis, with a case fatality rate of 8% (32/397). The mean annual incidence for the 304 culture-positive cases residing in metropolitan Salvador was 1.71 cases per 100,000 population. Infants <1 year old presented the highest incidence (14.7 cases per 100,000 population). Of the 377 serogrouped isolates, 82%, 16%, 2% and 0.3% were serogroups B, C, W135 and Y, respectively. A single serotype:serosubtype (4,7:P1.19,15) accounted for 64% of all cases. Continued surveillance is necessary to characterise strains and to define future prevention and control strategies.     

Suicide rates of migrants in United States immigration detention (2010–2020)

ObjectiveWe determined the annual suicide rate of migrants detained by U.S. Immigration and Customs Enforcement (ICE) in the past decade.MethodsWe performed a retrospective cohort analysis of the annual suicide rates for ICE detainees from federal fiscal years (FY) 2010–2020. Death date and cause of death were directly extracted from publicly available ICE Freedom of Information Act (FOIA) Library, ICE death reports, and ICE press releases. Annual suicide rates were calculated as suicides per 100,000 person-years and suicides per 100,000 admissions.ResultsFrom 2010–2019, the mean number of suicides per 100,000 person-years was 3.3 (standard deviation (SD): 2.6). In 2020, the suicide rate increased 5.3 times the prior 10-year average to 17.4 suicides per 100,000 person-years. When calculating suicide rate based on admissions per FY, the mean number of suicides from 2010–2019 per 100,000 admissions was 0.3 (SD: 0.3). In 2020, the suicide rate increased 11.0 times the prior 10-year average to 3.4 suicides per 100,000 admissions.ConclusionIn 2020, the detainee suicide rate increased substantially compared to the past decade. This may point to a worsening mental health crisis in ICE detention.     

1991-2018年济南市流行性脑脊髓膜炎流行特征及菌群变迁趋势分析

目的 分析济南市1991-2018年流行性脑脊髓膜炎（简称流脑）流行特征及菌群变迁趋势。方法 收集济南市1991-2018年疫情资料、2007-2016年急性脑炎脑膜炎症候群（AMES）监测数据和2008-2018年健康人群带菌状况调查资料进行流行病学分析。结果 1991-2018年济南市共报告流脑病例122例，年均发病率为0.07/10万；发病季节高峰期在1-5月（占80.32%）；发病以15岁以下儿童为主（占63.11%），15岁以上病例构成逐年增加；职业构成主要为学生、散居儿童和农民。2007-2016年AMES监测系统检出脑膜炎奈瑟菌阳性共33例，占报告病例的1.17%，其中B群20例，C群10例，W群1例，不可分群（NG）2例。2008-2018年健康人群流脑带菌状况调查，共检出34株流脑菌株，A群流脑菌株6株，B群5例株，C群8株，X群2株，Y群1株，W135群5株，NG7株，平均阳性率为0.89%。结论 济南市流脑疫情维持在较低水平，流脑优势菌群已发生变迁，现阶段控制以B群为主的发病流行，成为流脑防控工作的重点。     

合肥市2003～2012年流脑菌群变迁分析

目的了解合肥市流行性脑脊髓膜炎（简称流脑）菌群变迁情况,为流脑防治工作提供依据。方法对合肥市2000年至2012年流脑疫情和健康人群监测资料进行回顾性分析。结果2003年前,流脑病人主要由A群脑膜炎奈瑟菌引起（Nm）。健康人群带菌主要是B群Nm,其次为A群。2003—2012年流脑患者菌群,C群占93．0％,A群占6．O％,B群和W135占1．0％;健康人群带菌以c群和B群为主,分别为2．5％和1．6％。2011年出现由W135群引起的流脑死亡病例。结论2003—2012年,合肥市流脑流行优势菌群从A群Nm转变为C群,c群菌群Nm仍将在一段时间内是优势菌群,而W135群和B群为辅。     

The epidemiology of Neisseria meningitidis meningitis in Togo during 2003-2005

Few reports documenting the epidemiology of Neisseria meningitidis (Nm) serogroup W135 exist, and none from Togo. During 2003-2005, we conducted acute bacterial meningitis surveillance at three major reference hospitals in Togo. Of 116 Nm identified, 83 (71%) were NmA, 23 (20%) were NmW135, and 10 (9%) did not have a serogroup identified. Nine percent of NmW135 cases and 35% of NmA cases occurred among those aged 15 years or older. The two hospitals in central Togo reported 23% of all Nm cases and 78% of NmW135 cases. Twelve of the 23 NmW135 cases occurred during February-March 2003, while the remaining 11 occurred sporadically over the remaining 18 months of the study. NmW135 meningitis showed pronounced temporal and geographic clustering and occurred almost exclusively among those younger than 15 years old. By the 2004-2005 epidemic season, NmW135 had largely disappeared from Togo for unknown reasons.     

Response thresholds for epidemic meningitis in sub-Saharan Africa following the introduction of MenAfriVac®

BackgroundSince 2010, countries in the African meningitis belt have been introducing a new serogroup A meningococcal conjugate vaccine (MenAfriVac^®) through mass campaigns. With the subsequent decline in meningitis due to Neisseria meningitidis serogroup A (NmA) and relative increase in meningitis due to other serogroups, mainly N. meningitidis serogroup W (NmW), the World Health Organisation (WHO) initiated a review of the incidence thresholds that guide response to meningitis epidemics in the African meningitis belt.MethodsMeningitis surveillance data from African meningitis belt countries from 2002 to 2013 were used to construct a single NmW dataset. The performance of different weekly attack rates, used as thresholds to initiate vaccination response, on preventing further cases was estimated. The cumulative seasonal attack rate used to define an epidemic was also varied.ResultsConsiderable variation in effect at different thresholds was observed. In predicting epidemics defined as a seasonal cumulative incidence of 100/10⁵ population, an epidemic threshold of 10 cases/10⁵ population/week performed well. Based on this same epidemic threshold, with a 6 week interval between crossing the epidemic threshold and population protection from a meningococcal vaccination campaign, an estimated 17 cases per event would be prevented by vaccination. Lowering the threshold increased the number of cases per event potentially prevented, as did shortening the response interval. If the interval was shortened to 4 weeks at the threshold of 10/10⁵, the number of cases prevented would increase to 54 per event.ConclusionsAccelerating time to vaccination could prevent more cases per event than lowering the threshold. Once the meningitis epidemic threshold is crossed, it is of critical importance that vaccination campaigns, where appropriate, are initiated rapidly.     

Long-term impacts of MenC vaccination campaign in the Salvador,Brazil metropolitan region: A comparison of pre- and post-vaccine periods

The Meningococcal Serogroup C Conjugate Vaccine (MenC) was introduced into the Brazilian Immunization Program in 2010. However, in Salvador, the fourth largest capital in Brazil, an extended catch-up campaign was conducted earlier in that year, which focused on adolescents and young adults aged 10–24 years. To evaluate the long-term impact of MenC vaccination, we analyzed hospital-based surveillance data on cases of meningococcal disease in the Salvador metropolitan region during the pre-vaccine (2005–2009) and post-vaccine (2011–2016) campaign periods. Six years after the introduction of the MenC vaccine, the mean incidence rate decreased from 3.20 to 0.93 cases per 100,000 individuals (71% reduction, 95% CI [58.7–83.3]) in children <4 years. Reductions of 25.6% and 21.1% were also observed for the age groups of 5–9 and 10–14 years, respectively. On the other hand, incidence increased in the 15–24-year age group from 0.72 to 1.11, and from 0.31 to 0.60 in individuals aged >25 years (p < 0.05). At the end of the study period, serogroup C was the most prevalent (65.7%), followed by serogroups B (9.8%), W (2.3%), Y (1.6%) and A (1.0%); serogrouping was not possible in 19.6% of the cases, or adequate material was not available for serogroup identification. The use of real-time PCR from 2010 onwards increased detection rates of meningococcal meningitis by 29.6%. The long-term impact of the MenC vaccination campaign was associated with a significant reduction in MenC disease in children aged 0–4 years, yet no effect was observed in adolescents and adults, as evidenced by increasing trends in infection rates. In addition, the emergence of meningococcal serogroup A was identified, which should serve as an alert to public health officials and deserves further investigation.     

Emergence of serogroup X meningococcal disease in Africa: Need for a vaccine

Neisseria meningitidis is responsible for the seasonal burden and recurrent epidemics of meningitis in an area of sub-Saharan Africa known as the meningitis belt. Historically, the majority of the cases in the meningitis belt are caused by serogroup A meningococci. Serogroup C meningococci were responsible for outbreaks in the meningitis belt in the 1980s, while serogroup W (formerly W-135) has emerged as a cause of epidemic meningitis since 2000. Serogroup X meningococci have previously been considered a rare cause of sporadic meningitis, but during 2006–2010, outbreaks of serogroup X meningitis occurred in Niger, Uganda, Kenya,Togo and Burkina Faso, the latter with at least 1300 cases of serogroup X meningitis among the 6732 reported annual cases. While serogroup X has not yet caused an epidemic wave of the scale of serogroup A in 1996–1997 or serogroup W in Burkina Faso during 2002, the existing reports suggest a similar seasonal hyperendemicity and capacity for localised epidemics. Serogroup X incidence appears to follow a pattern of highly localised clonal waves, and in affected districts, other meningococcal serogroups are usually absent from disease. Currently, no licensed vaccine is available against serogroup X meningococci. Following the introduction of a monovalent serogroup A conjugate vaccine (MenAfriVac^®) in the meningitis belt and the upcoming introduction of pneumococcal conjugate vaccines, vaccine-based prevention of serogroup X may become a public health need. The serogroup X polysaccharide capsule is the most likely target for vaccine development, but recent data also indicate a potential role for protein-based vaccines. A multivalent vaccine, preferably formulated as a conjugate vaccine and covering at least serogroups A, W, and X is needed, and the efforts for vaccine development should be intensified.