How does the epidemiology of invasive meningococcal disease in the United States compare to that in Central Europe regarding incidence, age distribution, serogroup prevalence, seasonal patterns, and case‑fatality rates?

Meningococcal Disease Epidemiology: United States vs Central Europe

Incidence

The United States maintains substantially lower meningococcal disease incidence (0.18-0.3 per 100,000 population) compared to Central Europe (0.9 per 100,000 population), representing approximately a 3-fold difference. 1, 2

• US incidence declined from 1.1 per 100,000 in 1996 to 0.18 per 100,000 by 2013, representing historically low levels 1
• Central European (EU/EEA) countries reported an overall notification rate of 0.9 per 100,000 during 2004-2014, with annual decreases of 6.6% 2
• Both regions experienced declining trends across all age groups, though the US started from a lower baseline 3, 2

Age Distribution

Infants consistently bear the highest disease burden in both regions, though the magnitude differs substantially between the US and Central Europe. 1, 2

• In the US, infants <1 year have an incidence of 4.3 per 100,000, with the highest rates (5.3 per 100,000) in infants 0-5 months 1
• Central Europe reports infant incidence of 16.0 per 100,000, approximately 3-4 times higher than US rates 2
• Both regions show a secondary peak in adolescents and young adults, with 46% of US cases affecting children ≤2 years 1, 4
• The age distribution pattern is similar between regions, with declining incidence after infancy until the adolescent peak 1, 2

Serogroup Prevalence

Serogroup B dominates in both the US and Central Europe, but the proportional distribution differs significantly between regions. 1, 2

United States:

• Serogroup B, C, and Y each account for approximately one-third of cases 1
• Among children 0-59 months, serogroup B causes 60% of disease 1
• In persons ≥11 years, serogroups C, Y, or W cause 73% of cases 1
• During 2006-2015, serogroup distribution was: B (35.8%), Y (28.5%), C (22.8%), W (6.8%) 3

Central Europe:

• Serogroup B causes 74% of all cases, representing a much higher proportion than in the US 2
• Serogroup B predominates across all age groups in Europe 2
• Serogroup Y has been increasing in recent years, though remains less common than in the US 2, 5
• Countries with MCC vaccination programs showed dramatic decreases in serogroup C disease 1, 2

Seasonal Patterns

Both regions demonstrate similar seasonal variation, with peak incidence in late winter/early spring. 1, 4

• US data shows highest attack rates in February and March, with lowest rates in September 4
• This seasonal pattern is consistent across both regions, reflecting the respiratory transmission dynamics of N. meningitidis 1

Case-Fatality Rates

Case-fatality rates are comparable between the US and Central Europe, ranging from 10-20% overall, with higher mortality in specific high-risk populations. 1, 4

• US case-fatality rate is approximately 12-15% across all age groups 1, 4
• Persons with functional or anatomic asplenia experience dramatically higher case-fatality rates of 40-70% in both regions 1
• The case-fatality rate varies by serogroup and age, but overall mortality remains consistent between regions 4, 2

Vaccination Impact

The introduction of conjugate vaccines has differentially impacted epidemiology between regions based on timing and target populations. 1, 3

• In the US, MenACWY vaccination of adolescents (introduced 2005) led to a 76% decline in serogroups A, C, W, and Y among persons aged 11-20 years between 2006-2010 and 2011-2015 3
• Central European countries that introduced MCC vaccination before 2004 or during 2004-2014 showed decreasing serogroup C trends, while countries without routine MCC vaccination did not 2
• The UK, Netherlands, and Belgium demonstrated substantial herd immunity effects from adolescent catch-up campaigns, which Spain did not achieve with infant-only programs 1
• Vaccine effectiveness wanes after 1 year in infants vaccinated at 2,3, and 4 months in both regions, raising questions about optimal vaccination schedules 1

Key Epidemiologic Differences

The most striking difference is the 3-fold higher overall incidence in Central Europe compared to the US, particularly pronounced in infants, alongside the much higher proportion of serogroup B disease in Europe (74% vs 36%). 1, 2

• Serogroup Y is more prominent in the US (28.5% of cases) compared to Central Europe, where it remains uncommon despite recent increases 3, 2, 5
• Both regions show declining trends in all serogroups, including serogroup B despite lack of widespread vaccination until recently 1, 2
• Outbreak-associated cases account for only 1.5% of US cases, with sporadic disease predominating in both regions 1