Meningococcal C conjugate age-dependant long-term loss of effectiveness

Invasive Meningococcal Disease epidemiology and vaccination strategies in four Southern European countries: a review of the available data

INTRODUCTION

Invasive meningococcal disease (IMD) is a major health concern which can be prevented through vaccination. Conjugate vaccines against serogroups A, C, W and Y and two protein-based vaccines against serogroup B are currently available in the European Union.

AREAS COVERED

We present epidemiologic data for Italy, Portugal, Greece and Spain using publicly available reports from national reference laboratories and national or regional immunization programs (1999-2019), aiming to confirm risk groups, and describe time trends in overall incidence and serogroup distribution, as well as impact of immunization. Analysis of circulating MenB isolates in terms of the surface factor H binding protein (fHbp) using PubMLST is discussed as fHbp represents an important MenB vaccine antigen. Predictions of potential reactivity of the two available MenB vaccines (MenB-fHbp and 4CMenB) with circulating MenB isolates are also provided as assessed using the recently developed MenDeVAR tool.

EXPERT OPINION

Understanding dynamics of IMD and continued genomic surveillance are essential for evaluating vaccine effectiveness, but also prompting proactive immunization programs to prevent future outbreaks. Importantly, the successful design of further effective meningococcal vaccines to fight IMD relies on considering the unpredictable epidemiology of the disease and combining lessons learnt from capsule polysaccharide vaccines and protein-based vaccines.

Systematic literature review of the impact and effectiveness of monovalent meningococcal C conjugated vaccines when used in routine immunization programs

BACKGROUND

Monovalent meningococcal C conjugate vaccine (MCCV) was introduced into the routine immunization program in many countries in Europe and worldwide following the emergence of meningococcal serogroup C (MenC) in the late 1990s. This systematic literature review summarizes the immediate and long-term impact and effectiveness of the different MCCV vaccination schedules and strategies employed.

METHODS

We conducted a systematic literature search for peer-reviewed, scientific publications in the databases of MEDLINE (via PubMed), LILACS, and SCIELO. We included studies from countries where MCCV have been introduced in routine vaccination programs and studies providing the impact and effectiveness of MCCV published between 1st January 2001 and 31st October 2017.

RESULTS

Forty studies were included in the review; 30 studies reporting impact and 17 reporting effectiveness covering 9 countries (UK, Spain, Italy, Canada, Brazil, Australia, Belgium, Germany and the Netherlands). Following MCCV introduction, significant and immediate reduction of MenC incidence was consistently observed in vaccine eligible ages in all countries with high vaccine uptake. The reduction in non-vaccine eligible ages (especially population > 65 years) through herd protection was generally observed 3-4 years following introduction. Vaccine effectiveness (VE) was mostly assessed through screening methods and ranged from 38 to 100%. The VE was generally highest during the first year after vaccination and waned over time. The VE was better maintained in countries employing catch-up campaigns in older children and adolescents, compared to routine infant only schedules.

CONCLUSIONS

MCCV were highly effective, showing a substantial and sustained decrease in MenC invasive meningococcal disease. The epidemiology of meningococcal disease is in constant transition, and some vaccination programs now include adolescents and higher valent vaccines due to the recent increase in cases caused by serogroups not covered by MCCV. Continuous monitoring of meningococcal disease is essential to understand disease evolution in the setting of different vaccination programs.

Towards Predicting Protective Vaccine Responses in the Very Young

Infectious diseases remain a major cause of death in infancy. Vaccination is a proven-effective strategy to reduce the risk of infectious diseases. However, important gaps remain in our understanding of vaccine responses in early life. Systems vaccinology has provided new insight into mechanisms and predictors of vaccine responses. However, systems vaccinology has not yet been systematically applied to infants younger than 12 months of age. Here, we review the knowledge gained from systems vaccinology studies of vaccines that are licensed for administration to infants. We propose that systems vaccinology should be applied to age-specific studies focused on protection, to derive the necessary insight for optimal design of vaccines for the very young.

[Meningococcal C conjugate vaccine: Impact of a vaccination program and long-term effectiveness in Navarra, Spain, 2000-2014]

BACKGROUND

Since 2000, when the meningococcal serogroupC conjugate vaccine (MenCC) was introduced in the childhood immunization schedule in Spain, several changes in the schedule and catch-up campaigns have been performed. We aim to estimate the impact and effectiveness of this vaccine in Navarra up to 2014.

METHODS

The impact of the vaccination program was analysed by comparing incidence, mortality and lethality rates of disease before (1995-1999) and after (2004-2014) the introduction of the MenCC. Vaccine effectiveness was estimated using the screening method (Farrington) and the indirect cohort method (Broome). Data on cases were obtained from the active surveillance of meningococcal disease.

RESULTS

During 1995-1999 the mean annual incidence of meningococcalC disease was 1.32 per 100,000, and 7.18 per 100,000 in children younger than 15years. The fall of meningococcalC disease incidence was significant in cohorts targeted for vaccination from the beginning and progressive in the general population. No cases were reported between 2011 and 2014. The estimated vaccine effectiveness was 96% by the screening method, and 99% by the indirect cohort method.

CONCLUSION

The MenCC vaccination program has been successful in decreasing the incidence rate of serogroupC meningococcal disease in Navarra, and schedule changes have maintained high vaccine effectiveness throughout the study period.