Pneumococcal serotypes in children in 4 European countries

Area of Science:

• Microbiology
• Epidemiology
• Vaccinology

Background:

• The introduction of the heptavalent pneumococcal conjugate vaccine (PCV7) aimed to reduce invasive pneumococcal disease (IPD).
• Post-marketing surveillance is crucial to monitor vaccine impact and potential shifts in pathogen serotypes.

Purpose of the Study:

• To investigate the incidence of non-PCV7 serotypes (NVT) invasive pneumococcal disease following PCV7 introduction in France, Spain, Belgium, and the UK.
• To compare serotype-specific incidences before and after PCV7 marketing and assess the impact of vaccine coverage.

Main Methods:

• Comparative analysis of adjusted serotype-specific incidences of IPD in children under 15 years.
• Data collected from prevaccine (1999-2002) and postmarketing (2005-2006) periods.
• Calculation of incidence rate ratios (IRR) to assess changes in disease frequency.

Main Results:

• Invasive disease from NVT serotypes increased across all studied countries.
• Serotype 1 incidence rose independently of PCV7 use (IRR 1.3-4.2).
• Serotypes 7F and 19A showed the most significant increase in countries with higher PCV7 coverage (France, Spain, Belgium) (IRR 1.9-16.9).

Conclusions:

• PCV7 introduction was associated with an increase in NVT IPD, potentially due to vaccine-induced serotype replacement.
• Secular trends may also contribute to observed serotype dynamics.
• Further research is needed to understand serotype dynamics, considering underreporting and baseline trends, to inform the development of new vaccines.