[Paediatric Invasive Pneumococcal Disease Before Universal Vaccination: 1995 - 2015]

Area of Science:

• Pediatric Infectious Diseases
• Microbiology
• Vaccinology

Background:

• Pneumococcal conjugate vaccine (PCV) introduced to Portugal's private market in 2001, with national program inclusion in 2015.
• Moderate PCV coverage achieved prior to national program inclusion.
• Study focuses on invasive pneumococcal disease (IPD) in children before universal PCV use.

Purpose of the Study:

• Characterize IPD epidemiology in a Portuguese pediatric hospital.
• Establish a baseline for evaluating the impact of PCV introduction.
• Analyze trends in IPD diagnoses and causative serotypes.

Main Methods:

• Retrospective analysis of medical records (1995-2015).
• Inclusion of children with Streptococcus pneumoniae identified via culture and/or molecular biology from sterile sites.
• Evaluation of demographic, clinical, and microbiological data, including serotype information from 2004.

Main Results:

• 112 IPD cases identified over 20 years, median age 15 months.
• Highest case numbers observed between 2001-2002 and 2007-2012.
• Most frequent diagnoses: pneumonia (38%), occult bacteremia (34%), meningitis (21%).
• Increase in pneumonia and occult bacteremia diagnoses noted, potentially due to enhanced detection methods.

Conclusions:

• No reduction in overall IPD cases over two decades.
• Increased detection of pneumonia and occult bacteremia possibly linked to molecular diagnostic methods.
• Vaccine serotypes were predominant among identified isolates.
• This pre-universal vaccination data provides a crucial baseline for future impact assessments.