Do differences in infant vaccine requirements between Europe and the United States (USA) lead to a higher incidence of vaccine-preventable diseases in European infants?

Vaccine Schedule Differences Do Not Cause More Disease in Europe

The evidence does not support that differences in infant vaccine requirements between Europe and the USA result in higher disease incidence in European infants. Both regions maintain effective vaccination programs with comparable coverage for core vaccines, and disease burden differences are driven more by specific vaccine adoption timing, coverage rates, and herd immunity effects rather than fundamental schedule differences. 1, 2

Key Similarities Outweigh Differences

Core Vaccine Consensus

• All 32 European countries and the USA recommend the same 9 core vaccines: diphtheria, tetanus, pertussis, polio, Haemophilus influenzae type b, hepatitis B, measles, mumps, and rubella 1, 2
• These vaccines account for 45% of all available pediatric vaccines and represent the diseases with highest morbidity and mortality 2
• The total number of vaccines on national schedules ranges from 11-18 across Europe and the USA, showing relatively narrow variation 2

Dosing Patterns Show Agreement

• For 84.2% of vaccines with general recommendations, there is consistent dosing (same number of doses) across at least 50% of countries 2
• Age of first dose shows general agreement for most vaccines, with notable exceptions being meningococcal, hepatitis B, and COVID-19 vaccines 2

Where Differences Exist and Their Impact

Meningococcal Vaccination Variations

The most instructive example comes from meningococcal conjugate vaccine (MCC) implementation across Europe, which demonstrates that different schedules can achieve similar outcomes through herd immunity effects:

• UK, Ireland, and Spain initially used infant schedules (2,3,4 months), but vaccine effectiveness waned to low levels after only 1 year in infants 3
• Netherlands and Belgium used single-dose schedules at 12-14 months, which proved more cost-effective and provided longer-term protection 3
• Despite different approaches, both strategies successfully protected infants through herd immunity when adolescent catch-up campaigns were included 3

Critical Lesson on Herd Immunity

• Countries that included adolescent vaccination (ages 17-25) in catch-up campaigns achieved superior herd immunity by reducing carriage rates 3
• Spain, which initially only targeted children up to age 6, experienced less herd immunity benefit compared to UK and Netherlands 3
• This demonstrates that population-level protection depends more on comprehensive age-group coverage than specific infant schedules 3

Regulatory Framework Variations

Mandatory vs. Recommended Approaches

• As of 2024,13 European countries have at least one mandatory pediatric vaccination, while 17 rely solely on recommendations 4
• Between 2014-2024, six countries (Croatia, France, Germany, Hungary, Italy, Poland) introduced or extended mandatory vaccinations in response to declining coverage 4
• The USA and 21 European countries implement mandatory vaccinations, primarily for the core vaccines listed above 1

Impact on Coverage

• Mandatory policies were adopted specifically to combat vaccine hesitancy and declining coverage rates that led to VPD resurgence 4, 5
• Countries with robust healthcare systems, public trust, and adaptable strategies maintain high coverage regardless of mandate status 4

Disease Burden Considerations

No Evidence of Systematic European Disadvantage

The available evidence does not demonstrate that European infants experience higher rates of vaccine-preventable diseases due to schedule differences:

• Vaccination programs in both regions are "basically very safe and effective" 6
• Disease outbreaks in Europe (2009-2017) were attributed to insufficient coverage due to vaccine hesitancy, not schedule inadequacy 5
• When coverage rates drop below herd immunity thresholds, outbreaks occur regardless of whether schedules match USA recommendations 5

Schedule Flexibility Can Be Advantageous

• European experience with MCC vaccines demonstrated that later vaccination (12-14 months) provided longer-term protection than infant schedules 3
• Countries can successfully protect high-risk infant populations through indirect protection when overall population coverage is maintained 3

Common Pitfalls to Avoid

Confusing Schedule Differences with Coverage Gaps

• The primary driver of disease resurgence is inadequate coverage, not schedule variation 4, 5
• Focus should be on achieving and maintaining coverage above herd immunity thresholds rather than schedule harmonization 3

Overlooking Herd Immunity Effects

• Infant protection can be achieved through population-level immunity even with delayed individual vaccination 3
• Adolescent vaccination is crucial for reducing carriage and protecting vulnerable populations 3

Assuming One-Size-Fits-All Schedules

• Each country must adapt schedules to local epidemiology, healthcare infrastructure, and cultural context 4, 6
• Changes to vaccination schedules are costly and should only be implemented when evidence supports overall program improvement 6

Practical Implications

European vaccination programs do not cause more disease through schedule differences; rather, both Europe and the USA face similar challenges with vaccine hesitancy and maintaining adequate coverage. The evidence shows that multiple schedule approaches can achieve equivalent protection when coverage rates remain high and herd immunity is maintained through comprehensive age-group targeting 3, 1, 2.