Meningococcal conjugate vaccines: optimizing global impact

Public health perspective of a pentavalent meningococcal vaccine combining antigens of MenACWY-CRM and 4CMenB

OBJECTIVES

Invasive meningococcal disease (IMD) is a life-threatening disease that can rapidly progress to death or leave survivors with severe, life-long sequelae. Five meningococcal serogroups (A, B, C, W and Y) account for nearly all IMD. Meningococcal serogroup distribution fluctuates over time across the world and age groups. Here, we consider the potential public health impact of a pentavalent MenABCWY vaccine developed to help further control meningococcal disease and improve immunisation rates.

RESULTS

The GSK MenABCWY vaccine combines the antigenic components of MenACWY-CRM (Menveo®) and 4CMenB (Bexsero®), building on a wide body of clinical experience and real-world evidence. Both approved vaccines have acceptable safety profiles, demonstrate immunogenicity, and are broadly used, including in national immunisation programmes in several countries. Since the advent of quadrivalent vaccines, public health in relation to IMD has improved, with a decline in the overall incidence of IMD and an increase in vaccine coverage.

CONCLUSION

A pentavalent MenABCWY has the potential to provide further public health benefits through practical, broad IMD protection programmes encompassing serogroups A, B, C, W and Y, and is currently in late-stage development.

Vaccine-preventable infections in Systemic Lupus Erythematosus

Systemic Lupus Erythematosus (SLE) is characterized by abnormal autoantibody production and clearance. Infections are among the most important causes of morbidity and mortality in SLE patients; they have an increased frequency of severe bacterial and viral infections possibly due to inherited genetic and immunologic defects and to immunosuppressive therapies. In addition, infectious agents can switch on lupus disease expression and activity. Among the strategies to reduce the risk of infection, vaccination can be considered the most reliable option. Most vaccines are effective and safe in SLE patients, although in certain cases immunogenicity may be sub-optimal and vaccination can trigger a flare. Although these issues are currently unresolved, the risk benefit balance is in favor for vaccination to reduce the risk of infection in SLE patients. In the present review we discuss the preventive strategies currently recommended to reduce bacterial and viral infections in SLE.

Meningococcal polysaccharide A O-acetylation levels do not impact the immunogenicity of the quadrivalent meningococcal tetanus toxoid conjugate vaccine: results from a randomized, controlled phase III study of healthy adults aged 18 to 25 years

In this study, we compared the immunogenicities of two lots of meningococcal ACWY-tetanus toxoid conjugate vaccine (MenACWY-TT) that differed in serogroup A polysaccharide (PS) O-acetylation levels and evaluated their immunogenicities and safety in comparison to a licensed ACWY polysaccharide vaccine (Men-PS). In this phase III, partially blinded, controlled study, 1,170 healthy subjects aged 18 to 25 years were randomized (1:1:1) to receive one dose of MenACWY-TT lot A (ACWY-A) (68% O-acetylation), MenACWY-TT lot B (ACWY-B) (92% O-acetylation), or Men-PS (82% O-acetylation). Immunogenicity was evaluated in terms of serum bactericidal activity using rabbit complement (i.e., rabbit serum bactericidal activity [rSBA]). Solicited symptoms, unsolicited adverse events (AEs), and serious AEs (SAEs) were recorded. The immunogenicities, in terms of rSBA geometric mean titers, were comparable for both lots of MenACWY-TT. The vaccine response rates across the serogroups were 79.1 to 97.0% in the two ACWY groups and 73.7 to 94.1% in the Men-PS group. All subjects achieved rSBA titers of ≥1:8 for all serogroups. All subjects in the two ACWY groups and 99.5 to 100% in the Men-PS group achieved rSBA titers of ≥1:128. Pain was the most common solicited local symptom and was reported more frequently in the ACWY group (53.9 to 54.7%) than in the Men-PS group (36.8%). The most common solicited general symptoms were fatigue and headache, which were reported by 28.6 to 30.3% and 26.9 to 31.0% of subjects, respectively. Two subjects reported SAEs; one SAE was considered to be related to vaccination (blighted ovum; ACWY-B group). The level of serogroup A PS O-acetylation did not affect vaccine immunogenicity. MenACWY-TT (lot A) was not inferior to Men-PS in terms of vaccine response and was well tolerated.

Timely detection of bacterial meningitis epidemics at district level: a study in three countries of the African Meningitis Belt

BACKGROUND

Bacterial meningitis is a major public health problem in the African 'Meningitis Belt', where recurrent unpredictable epidemics occur. Despite the introduction in 2010 of the conjugate A vaccine, the reactive strategy remains important for responding to epidemics caused by other bacteria and in areas not yet vaccinated. Review of weekly numbers of suspected cases in Niger, Mali and Burkina Faso identified spatial disparities in the annual patterns of meningitis, which suggested a more local way of defining epidemics and initiating a timely vaccination campaign.

METHOD

We defined an epidemic district-year as an excess of cases compared to the incidence previously experienced in the given district. Groups of similar districts in terms of seasonal patterns were identified by cluster analysis. We investigated a cluster-specific criterion of early epidemic onset to anticipate epidemic district-years.

RESULTS

These were encouraging, as epidemic district-years were fairly efficiently captured, with an average time gained of 2.5 weeks over the current strategy.

CONCLUSION

This early-onset criterion could help ensure timely implementation of vaccination campaigns without the need to modify the implemented surveillance system. The next step is to extend this study to other countries of the Meningitis Belt, and to explain the differences in seasonal patterns in the different clusters.

Safety of meningococcal polysaccharide-protein conjugate vaccine in pregnancy: a review of the Vaccine Adverse Event Reporting System

OBJECTIVE

We characterized reports to the Vaccine Adverse Event (AE) Reporting System (VAERS) of pregnant women who received meningococcal polysaccharide-protein conjugate vaccine Menactra (MenACWY-D; Sanofi Pasteur Inc., Swiftwater, PA).

STUDY DESIGN

We searched VAERS for reports of pregnant women who received MenACWY-D from Jan. 1, 2005 through Dec. 31, 2011. We conducted clinical review of reports and available medical records.

RESULTS

Of 103 identified reports, 38 (36.7%) did not describe any AE. No maternal or infant deaths were reported. The most frequent pregnancy-specific AE was spontaneous abortion in 17 (16.5%) reports. Urinary tract infections and fever with vomiting were the most frequent nonpregnancy-specific AEs found in 4 (3.9%) and 3 (2.9%) reports, respectively. We identified 1 report with a major congenital anomaly (aqueductal stenosis and severe ventriculomegaly).

CONCLUSION

Our comprehensive review of reports to VAERS in pregnant women after MenACWY-D did not identify any concerning patterns in maternal, infant, or fetal outcomes.

Passive smoking, invasive meningococcal disease and preventive measures: a commentary

Active smoking is a recognized risk factor of various infectious diseases. In a systematic review published in BMC Public Health, Murray et al. demonstrated that exposure to passive smoking significantly increased the risk of meningococcal disease among children. Their review especially highlights that the risk remains high even if the exposure occurs during pregnancy or after birth, although the authors could not disentangle the independent effects of smoking during pregnancy from those in the postnatal period. How passive smoking increases the risk of childhood meningococcal disease is not precisely known. Both exposure to 'smoke', or 'smokers' (who are highly susceptible to pharyngeal carriage of meningococci) are postulated mechanisms, but unfortunately very few studies have examined the risk of exposure by considering these two variables separately, and this therefore remains a research priority. Quitting may well be the mainstay of preventing tobacco-related hazards but the available global data suggest that most smokers are reluctant to quit. Among other interventions, immunizing children with a meningococcal conjugate vaccine could, theoretically, reduce the risk of meningococcal disease among children and their smoker household contacts through herd immunity. See related article http://www.biomedcentral.com/1471-2458/12/1062

Serogroup A meningococcal conjugate vaccination in Burkina Faso: analysis of national surveillance data

BACKGROUND

An affordable, highly immunogenic Neisseria meningitidis serogroup A meningococcal conjugate vaccine (PsA-TT) was licensed for use in sub-Saharan Africa in 2009. In 2010, Burkina Faso became the first country to implement a national prevention campaign, vaccinating 11·4 million people aged 1-29 years. We analysed national surveillance data around PsA-TT introduction to investigate the early effect of the vaccine on meningitis incidence and epidemics.

METHODS

We examined national population-based meningitis surveillance data from Burkina Faso using two sources, one with cases and deaths aggregated at the district level from 1997 to 2011, and the other enhanced with results of cerebrospinal fluid examination and laboratory testing from 2007 to 2011. We compared mortality rates and incidence of suspected meningitis, probable meningococcal meningitis by age, and serogroup-specific meningococcal disease before and during the first year after PsA-TT implementation. We assessed the risk of meningitis disease and death between years.

FINDINGS

During the 14 year period before PsA-TT introduction, Burkina Faso had 148 603 cases of suspected meningitis with 17 965 deaths, and 174 district-level epidemics. After vaccine introduction, there was a 71% decline in risk of meningitis (hazard ratio 0·29, 95% CI 0·28-0·30, p<0·0001) and a 64% decline in risk of fatal meningitis (0·36, 0·33-0·40, p<0·0001). We identified a statistically significant decline in risk of probable meningococcal meningitis across the age group targeted for vaccination (62%, cumulative incidence ratio [CIR] 0·38, 95% CI 0·31-0·45, p<0·0001), and among children aged less than 1 year (54%, 0·46, 0·24-0·86, p=0·02) and people aged 30 years and older (55%, 0·45, 0·22-0·91, p=0·003) who were ineligible for vaccination. No cases of serogroup A meningococcal meningitis occurred among vaccinated individuals, and epidemics were eliminated. The incidence of laboratory-confirmed serogroup A N meningitidis dropped significantly to 0·01 per 100 000 individuals per year, representing a 99·8% reduction in the risk of meningococcal A meningitis (CIR 0·002, 95% CI 0·0004-0·02, p<0·0001).

INTERPRETATION

Early evidence suggests the conjugate vaccine has substantially reduced the rate of meningitis in people in the target age group, and in the general population because of high coverage and herd immunity. These data suggest that fully implementing the PsA-TT vaccine could end epidemic meningitis of serogroup A in sub-Saharan Africa.

FUNDING

None.