Effectiveness of vaccinating household contacts in addition to chemoprophylaxis after a case of meningococcal disease: a systematic review

Twins with meningitis due to Neisseria meningitidis

Introduction

The incidence of invasive meningococcal disease is highest in infants and young children.

Case report

Twin infants diagnosed two days apart with meningitis due to N. meningitidis serogroup B are presented.

Conclusions

There has never been a report of concurrent meningococcal meningitis in twin brothers. We wanted to highlight the high likelihood of meningococcal transmission through household contacts and the importance of antibiotic prophylaxis and meningococcal vaccination recommendations for close contacts of these cases.

Two Cases of Meningococcal Disease in One Family Separated by an Extended Period - Colorado, 2015-2016

On April 26, 2015, a case of meningococcal disease in a woman aged 75 years was reported to the Colorado Department of Public Health and Environment (CDPHE). As part of routine public health investigation and control activities, all seven family contacts of the patient were advised to receive appropriate postexposure prophylaxis (PEP) to eradicate nasopharyngeal carriage of meningococci and prevent secondary disease (1), although it is not known whether the family contacts complied with PEP recommendations. Fifteen months later, on June 6, 2016, CDPHE was notified that the grandchild of the first patient, a male infant aged 3 months who lived with the first patient, also had meningococcal disease. The infant's immediate family members (parents and one sibling) were among family contacts for whom PEP was recommended in 2015. Neisseria meningitidis isolates from both patients were found to be serogroup C at the CDPHE laboratory. Whole genome sequence (WGS) analysis at CDC found that both isolates had the same sequence type, indicating close genetic relatedness. These cases represent a possible instance of meningococcal disease transmission within a family, despite appropriate PEP recommendations and with a long interval between cases.

European public health policies for managing contacts of invasive meningococcal disease cases better harmonised in 2013 than in 2007

In 2007, a European survey identified variation in country policies on public health management of invasive meningococcal disease (IMD). In 2009-10, the European Centre for Disease Prevention and Control (ECDC) published evidence-based guidance on IMD. We therefore surveyed again European countries to describe policies for managing IMD cases and contacts in 2013. We asked national IMD public health experts from 32 European countries to complete a questionnaire focusing on post-exposure prophylaxis (PEP) for IMD contacts and meningococcal vaccination. Proportions in 2007 and 2013 were compared using the chi-squared test. All 32 countries responded, with responses from two regions for Belgium and Italy; half stated having used ECDC guidance to update national recommendations. PEP was recommended to close contacts in 33 of 34 countries/regions, mainly ciprofloxacin for adults (29/32 countries) and rifampicin for children (29/32 countries). ECDC guidance for managing IMD contacts in airplanes was strictly followed by five countries/regions. Twenty-three countries/regions participated in both surveys. Compared with 2007, in 2013, more countries/regions recommended i) ceftriaxone for children (15/23 vs 6/20; p = 0.03), ii) PEP for all children in the same preschool group (8/23 vs 17/23; p = 0.02). More countries/regions recommended evidence-based measures for IMD public health management in 2013 than 2007. However, some discrepancies remain and they call for further harmonisation.

Background Paper for the update of meningococcal vaccination recommendations in Germany: use of the serogroup B vaccine in persons at increased risk for meningococcal disease

In December 2013 Bexsero® became available in Germany for vaccination against serogroup B meningococci (MenB). In August 2015 the German Standing Committee on Vaccination (STIKO) endorsed a recommendation for use of this vaccine in persons at increased risk of invasive meningococcal disease (IMD). This background paper summarizes the evidence underlying the recommendation. Bexsero® is based on surface protein antigens expressed by about 80% of circulating serogroup B meningococci in Germany. The paper reviews available data on immunogenicity and safety of Bexsero® in healthy children and adolescents; data in persons with underlying illness and on the effectiveness in preventing clinical outcomes are thus far unavailable.STIKO recommends MenB vaccination for the following persons based on an individual risk assessment: (1) Persons with congenital or acquired immune deficiency or suppression. Among these, persons with terminal complement defects and properdin deficiency, including those under eculizumab therapy, are at highest risk with reported invasive meningococcal disease (IMD) incidences up 10,000-fold higher than in the general population. Persons with asplenia were estimated to have a ~ 20-30-fold increased risk of IMD, while the risk in individuals with other immune defects such as HIV infection or hypogammaglobulinaemia was estimated at no more than 5-10-fold higher than the background risk. (2) Laboratory staff with a risk of exposure to N. meningitidis aerosols, for whom an up to 271-fold increased risk for IMD has been reported. (3) Unvaccinated household (-like) contacts of a MenB IMD index case, who have a roughly 100-200-fold increased IMD risk in the year after the contact despite chemoprophylaxis. Because the risk is highest in the first 3 months and full protective immunity requires more than one dose (particularly in infants and toddlers), MenB vaccine should be administered as soon as possible following identification of the serogroup of the index case.

Chemoprophylaxis and vaccination in preventing subsequent cases of meningococcal disease in household contacts of a case of meningococcal disease: a systematic review

Household contacts of an index case of invasive meningococcal disease (IMD) are at increased risk of acquiring disease. In revising WHO guidance on IMD in sub-Saharan Africa, a systematic review was undertaken to assess the effect of chemoprophylaxis and of vaccination in preventing subsequent cases of IMD in household contacts following an index case. A literature search for systematic reviews identified a single suitable review on chemoprophylaxis in 2004 (three studies meta-analysed). A search for primary research papers published since 2004 on chemoprophylaxis and without a date limit on vaccination was therefore undertaken. There were 2381 studies identified of which two additional studies met the inclusion criteria. The summary risk ratio for chemoprophylaxis vs. no chemoprophylaxis (four studies) in the 30-day period after a case was 0·16 [95% confidence interval (CI) 0·04-0·64, P = 0·008]; the number needed to treat to prevent one subsequent case was 200 (95% CI 111-1000). A single quasi-randomized trial assessed the role of vaccination. The risk ratio for vaccination vs. no vaccination at 30 days was 0·11 (95% CI 0·01-2·07, P = 0·14). The results support the use of chemoprophylaxis to prevent subsequent cases of IMD in household contacts of a case. Conclusions about the use of vaccination could not be drawn.

Preventing secondary cases of invasive meningococcal capsular group B (MenB) disease using a recently-licensed, multi-component, protein-based vaccine (Bexsero(®))

OBJECTIVES

To assess the potential use of a protein-based meningococcal group B (MenB) vaccine (Bexsero(®)) in addition to antibiotic chemoprophylaxis for preventing secondary cases.

METHODS

Published studies on the risk of secondary meningococcal infections were used to estimate the numbers needed to vaccinate (NNV) with Bexsero(®) to prevent a secondary case in household and educational settings.

RESULTS

Most secondary cases occur within a few days of diagnosis in the index case. Unlike conjugate vaccines, early protection offered after a single dose of Bexsero(®) is likely to be low, particularly in young children, who are at higher risk of secondary infection. NNV was dependent on predicted meningococcal strain coverage, estimated onset of protection after one Bexsero(®) dose and estimated vaccine efficacy. Even in the most favourable scenario where we assume the vaccine is administered within 4 days of the index case and prevents 90% of cases occurring after 14 days, the NNV for household contacts was >1000. NNV in educational settings was much higher.

CONCLUSIONS

The estimated NNV should be taken into account when deciding policy to recommend Bexsero(®) for close contacts of single cases in household or educational settings. Bexsero(®) may have a protective role in clusters and outbreaks.

Meningococcal disease serogroup C

Despite current advances in antibiotic therapy and vaccines, meningococcal disease serogroup C (MDC) remains a serious threat to global health, particularly in countries in North and Latin America, Europe, and Asia. MDC is a leading cause of morbidity, mortality, and neurological sequelae and it is a heavy economic burden. At the individual level, despite advances in antibiotics and supportive therapies, case fatality rate remains nearly 10% and severe neurological sequelae are frequent. At the population level, prevention and control of infection is more challenging. The main approaches include health education, providing information to the public, specific treatment, chemoprophylaxis, and the use of vaccines. Plain and conjugate meningococcal C polysaccharide vaccines are considered safe, are well tolerated, and have been used successfully for over 30 years. Most high-income countries use vaccination as a part of public health strategies, and different meningococcal C vaccination schedules have proven to be effective in reducing incidence. This is particularly so with conjugate vaccines, which have been found to induce immunogenicity in infants (the age group with the highest incidence rates of disease), stimulate immunologic memory, have longer effects, not lead to hyporesponsiveness with repeated dosing, and decrease acquisition of nasopharyngeal carriage, inducing herd immunity. Antibiotics are considered a cornerstone of MDC treatment and must be administered empirically as soon as possible. The choice of which antibiotic to use should be made based on local antibiotic resistance, availability, and circulating strains. Excellent options for a 7-day course are penicillin, ampicillin, chloramphenicol, and third-generation cephalosporins (ceftriaxone and cefotaxime) intravenously, although the latter are considerably more expensive than the others. The use of steroids as adjunctive therapy for MDC is still controversial and remains a topic of debate. A combination of all of the aforementioned approaches is useful in the prevention and control of MDC, and each country should tailor its public health policy to its own particular needs and knowledge of disease burden.

European efforts to harmonize typing of meningococci

Neisseria meningitidis causes life-threatening disease in infants, toddlers, and adolescents. Besides representative case notification, public health management of the disease requires bacterial typing information. European reference laboratories and state epidemiologists in collaboration with European institutions have driven forward the harmonization of typing by rigorously adopting DNA sequence typing and using common reference databases. External quality assessment has been provided by supranational networks, i.e. EU-IBIS and IBD-Labnet. The recent development of novel protein-based vaccines targeting serogroup B strains highlights the necessity to complement standard typing schemes by specific vaccine antigen typing including antigen expression analysis. Although not yet feasible for routine application on hundreds of strains, novel database structures have been developed to accommodate deep sequencing data.

What is the evidence for giving chemoprophylaxis to children or students attending the same preschool, school or college as a case of meningococcal disease?

We performed a systematic literature review to assess the effectiveness of chemoprophylaxis for contacts of sporadic cases of invasive meningococcal disease (IMD) in educational settings. No studies directly compared IMD risk in contacts with/without chemoprophylaxis. However, compared to the background incidence, an elevated IMD risk was identified in settings without a general recommendation for chemoprophylaxis in pre-schools [pooled risk difference (RD) 58·2/10⁵, 95% confidence interval (CI) 27·3-89·0] and primary schools (pooled RD 4·9/10⁵, 95% CI 2·9-6·9) in the ~30 days after contact with a sporadic IMD case, but not in other educational settings. Thus, limited but consistent evidence suggests the risk of IMD in pre-school contacts of sporadic IMD cases is significantly increased above the background risk, but lower than in household contacts (pooled RD for household contacts with no chemoprophylaxis vs. background incidence: 480·1/10⁵, 95% CI 321·5-639·9). We recommend chemoprophylaxis for pre-school contacts depending on an assessment of duration and closeness of contact.