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

ABSTRACT

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.

KEYWORDS:

• Factor H binding protein
• invasive meningococcal disease
• MenDeVAR
• neisseria meningitidis
• serogroup
• Southern europe
• vaccine

Acknowledgments

Medical writing support was provided by Athena Georgilis and Panagiota Karagianni at Qualitis SA and was funded by Pfizer.

Part of this work has been presented as an abstract in the 40th Annual meeting of the European Society of Infectious Diseases (ESPID) 2022.

Article highlights

• Based on epidemiological data from the past two decades, infants represent individuals most affected by IMD in Italy, Portugal, Greece and Spain, followed by toddlers and young children. A small yet consistent peak is observed during adolescence and young adulthood in certain countries.

• Incidence of IMD in Portugal, Greece, and Spain has been declining, while Italy shows relatively stable trends over the examined period. Small surges in IMD rates continue to appear, with temporal and geographical variation.

• Over the past two decades, the most prominent disease-causing meningococcal serogroup in the four Southern European countries is B, while increases in prevalence of serogroup Y and W are also observed.

• Since the immunization with MenC vaccines in the early 2000s, MenC cases have been declining, while MenB remains the predominant cause of IMD in all four countries, with two protein-based MenB vaccines, 4CMenB and MenB-fHbp, only recently being introduced in routine practice.

• fHbp, generally classified into two immunogenically distinct subfamilies A and B, represents an important MenB vaccine antigen, consistently present across circulating MenB isolates in Italy, Portugal, Greece and Spain. Variants of both subfamilies A and B, but with observed differences in distribution were detected across countries and years.

• The 4CMenB vaccine is designed to target fHbp peptides of subfamily B, while peptides of both A and B, are targetable by the MenB-fHbp vaccine. Based on in silico predictions, 54.3-75.3% of circulating MenB isolates across the four countries are potentially reactive with MenB-fHbp and 20.4-54% are potentially reactive with 4CMenB.

Declaration of interest

All authors are Pfizer employees and may hold stock options. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or material discussed in the manuscript apart from those disclosed.

Reviewer disclosures

A reviewer on this manuscript has disclsed that they perform contract research on behalf of UK Health Security Agency for GSK, Pfizer and Sanofi Pasteur. Peer reviewers on this manuscript have no other relevant financial or other relationships to disclose.

Author contributions

All authors have substiantially contributed to to the conception and design of the review article and interpreting the relevant literature and have been involved in writing the review article or revised it for intellectual content.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/14760584.2023.2225596

Additional information

Funding

This work was supported by Pfizer.