Effectiveness of the new serotypes in the 13-valent pneumococcal conjugate vaccine

Area of Science:

• * Pediatric infectious diseases
• * Vaccinology and immunology
• * Public health surveillance

Background:

• * The 13-valent pneumococcal conjugate vaccine (PCV13) was introduced to broaden protection against invasive pneumococcal disease (IPD) beyond the original 7-valent vaccine (PCV7).
• * Efficacy of new serotypes in PCV13 was initially based on a putative correlate of protection, necessitating real-world effectiveness evaluation.
• * In England and Wales, PCV13 replaced PCV7 in the infant immunization schedule in April 2010.

Purpose of the Study:

• * To estimate the vaccine effectiveness (VE) of the additional serotypes included in PCV13 against IPD.
• * To assess the impact of PCV13 introduction on IPD incidence caused by serotypes covered exclusively by PCV13.

Main Methods:

• * A case-control study design was employed using IPD cases in PCV13-eligible children.
• * Non-vaccine type IPD cases served as controls to estimate VE for the new serotypes.
• * Data included serotype and vaccination status from 166 IPD cases reported by July 2011.

Main Results:

• * Vaccine effectiveness (VE) for PCV13 against IPD was estimated for different dosing schedules and specific serotypes.
• * For two doses before one year of age, VE was 78%; for one dose over one year, VE was 77%.
• * VE for serotypes 7F and 19A was 76% and 70% respectively. IPD due to PCV13-only serotypes decreased by 50% in children under two years.

Conclusions:

• * PCV13 demonstrated significant effectiveness in reducing invasive pneumococcal disease (IPD) in young children in England and Wales.
• * The vaccine provided substantial protection against serotypes 7F and 19A, contributing to the overall reduction in IPD.
• * The introduction of PCV13 led to a halving of IPD cases caused by serotypes exclusively covered by the 13-valent vaccine.