Meningococcal Disease Epidemiology in Central Europe
Invasive meningococcal disease (IMD) in Central Europe has shown declining overall incidence over the past two decades, with serogroup B remaining predominant, but recent increases in serogroups W and Y—particularly affecting older adults—signal important epidemiological shifts that warrant attention.
Overall Incidence and Trends
The overall notification rate of IMD across EU/EEA countries was 0.9 per 100,000 population during 2004-2014, with an annual decrease of 6.6% 1. Between 2008 and 2017, overall IMD incidence decreased by 34.4% across Europe 2. However, this declining trend has not been uniform across all serogroups or age groups, and recent data suggest stabilization or reversal in certain populations 3.
Central European countries specifically (including Germany, Czech Republic, Poland, Hungary) have generally experienced lower notification rates than the European average, though distinct patterns exist within individual nations 4.
Serogroup Distribution
Serogroup B Dominance
Serogroup B remains the predominant cause of IMD in Central Europe, accounting for 74% of all cases across the EU/EEA during the surveillance period 1. In Germany specifically, serogroup B incidence in persons under 25 years decreased from 0.63 to 0.32 per 100,000 between 2002 and 2010 5. Despite this decline of 56.1% between 2008 and 2017, the rate of decrease has slowed in recent years and varies considerably by age group 2.
Serogroup C Decline
Serogroup C was the second most prevalent serogroup until 2016 2. Countries that introduced meningococcal C conjugate (MCC) vaccination before or during 2004-2014 experienced significant decreasing trends in serogroup C disease, while countries without routine MCC vaccination did not show similar declines 1.
In Germany, serogroup C incidence in persons under 25 years decreased from 0.26 to 0.10 per 100,000 between 2002 and 2010 5. The decline was significantly steeper for serogroup C than serogroup B in 1-5 year-olds (the primary vaccination target group), and states with higher vaccination uptake showed steeper decreases in incidence 5. However, increases in serogroup C have occurred in age groups outside the 1-24 year range targeted by vaccination campaigns 2.
Emerging Serogroups W and Y
A critical epidemiological shift has been the dramatic rise in serogroups W and Y. Between 2008 and 2017, serogroup W incidence increased by more than 500% (to 0.10 per 100,000) and serogroup Y increased by more than 130% (to 0.07 per 100,000) 2.
From 2013 to 2017, serogroup W incidence per 100,000 population increased from 0.03 to 0.11, and the proportion among all invasive cases rose from 5% to 19% 3. The most affected countries were England, the Netherlands, Switzerland, and Sweden, with 80% of culture-confirmed serogroup W cases caused by the hypervirulent clonal complex 11 (cc11) 3.
In Belgium, Spain, France, the Netherlands, the UK, and Portugal, incidence was greater for serogroup W than serogroup C by 2019 6.
Age Distribution
Infants consistently have the highest incidence of IMD, with a rate of 16.0 per 100,000 population 1. Decreasing trends were observed in all age groups under 50 years during 2004-2014 1.
However, a marked modification of evolution trends by age group has occurred since 2008, with increases in incidence mainly affecting older age groups 2. Serogroup W was more frequent in older age groups (≥45 years), while the proportion in children (<15 years) was lower than in other age groups 3. The age distribution shows highest rates in infants and children, with a further peak in adolescents and young adults in most Central European countries 4.
Vaccination Impact
MCC Vaccination Success
All European countries that introduced routine MCC vaccination experienced substantial declines in serogroup C disease incidence 7. A striking feature of MCC vaccination programs in England and the Netherlands was the additional decrease in disease incidence resulting from herd immunity 7.
In Germany, the effects of the serogroup C vaccination strategy (targeting one-year-olds since 2006 with catch-up to 17 years) appeared limited, though interpretation is complicated by already low and decreasing incidence before vaccination implementation 5. The slope of serogroup C incidence curves was similar before and after vaccination implementation in all age groups 5.
Serogroup B Vaccination
Following introduction of the serogroup B vaccine into the UK vaccine program, a recent surveillance study reported a 50% incidence ratio reduction, indicating substantial effect of the vaccination campaign 7. As of 2019, serogroup B risk was covered in only 2 countries (Italy and UK) 6.
Seasonality and Geographic Variation
Serogroup A has caused remarkably few cases in Europe over recent decades, despite being common in the early 20th century 7. The last large serogroup A outbreak in Europe occurred in Finland in the 1970s, and disease has not re-established despite remaining endemic and epidemic in other parts of the world, particularly sub-Saharan Africa 7. The reasons for the disappearance of serogroup A in Europe are not clear 7.
Each individual Central European country has distinct patterns for serogroup distribution, with variations in epidemiology between countries despite similar economic resources and epidemiological risk factors 4.
Clinical Implications and Pitfalls
A common pitfall is assuming that declining overall IMD incidence means the threat is diminishing uniformly. The emergence of serogroups W and Y, particularly the hypervirulent cc11 clone, and the shift toward older age groups require vigilance 2, 3. Given the unpredictable nature of meningococcal spread and the epidemiological potential of cc11, European countries should consider preventive strategies adapted to their contexts 3.
Another important consideration is that declining serogroup C incidence was associated with decreased finetype diversity in Germany, suggesting selective pressure from vaccination 5. The phenomenon of serotype replacement observed with pneumococcal vaccines is a major concern for future meningococcal vaccination strategies 7.
Reduced susceptibility to penicillin has been described in multiple countries, and although most patients with intermediate susceptibility respond well to penicillin, worse outcomes have been documented 7. Recent data show a notable increase in fully penicillin-resistant isolates since 2016 and fluoroquinolone-resistant isolates since 2005 8.
Current Vaccination Coverage
Vaccination coverage rates are higher in children than adolescents across Central Europe 6. As of 2019, serogroup C risk was covered in all surveyed countries via MenC only (3 countries), MenACWY only (2 countries), or MenC for infants/children and MenACWY for adolescents (3 countries) 6.
The diversity of national immunization programs, even in neighboring European countries with similar factors, indicates that factors beyond economic resources and epidemiological risk underlie vaccination policy decisions 6.