Invasive Pneumococcal Disease After 2 Decades of Pneumococcal Conjugate Vaccine Use

Area of Science:

• Pediatric infectious diseases
• Vaccinology
• Epidemiology

Background:

• Invasive pneumococcal disease (IPD) remains a significant public health concern in children.
• The introduction of pneumococcal conjugate vaccines (PCV7 and PCV13) has aimed to reduce the burden of IPD.
• Understanding the evolving epidemiology of IPD is crucial for public health strategies.

Purpose of the Study:

• To describe the changing epidemiology of IPD in children in Massachusetts over 20 years.
• To assess the impact of PCV7 and PCV13 vaccine implementation on IPD incidence and serotype distribution.
• To monitor antimicrobial susceptibility patterns of Streptococcus pneumoniae isolates.

Main Methods:

• A population-based surveillance system tracked IPD cases in children (<18 years) from 2002 to 2021.
• Streptococcus pneumoniae isolates were serotyped and tested for antimicrobial susceptibility.
• Incidence rates and rate ratios were calculated to assess trends.

Main Results:

• Overall IPD incidence in children decreased by 72% between 2002 and 2021.
• Rates continued to decline after PCV13 replaced PCV7, reaching the lowest point during 2020-2021.
• Shifts in dominant serotypes were observed, with non-PCV13 serotypes becoming more prevalent and showing increased penicillin nonsusceptibility.

Conclusions:

• Sustained surveillance is essential for detecting emerging IPD serotypes.
• Vaccine development needs to consider the changing landscape of circulating pneumococcal strains.
• Ongoing monitoring informs vaccine policy and public health interventions.