Why carry out this study?

As novel pneumococcal conjugate vaccines (PCV) with greater serotype coverage are introduced into infant national immunization programs (NIP), it will be important to understand the current epidemiologic trends for these serotypes as well as for currently covered serotypes.

The objective of this study was to estimate the annual population-level impact of PCV13 NIPs on vaccine-type and non-vaccine type (NVT) invasive pneumococcal disease (IPD) incidence among children and adults using national surveillance data of countries that switched from PCV7 to PCV13 in their NIP.

What was learned from this study?

Infant PCV13 vaccination with high population-level uptake rates has led to substantial reductions in vaccine-type IPD in the first 7 years across all age groups following introduction in countries where the vaccine was introduced (i.e., both direct and indirect protection was observed). Conversely, an increase in NVT IPD was observed across all age groups.

The impact of PCV13 was more substantial in ages < 5 years compared with ages ≥ 65 years, illustrating the need for an adult PCV program covering many of the same serotypes as the pediatric PCV program rather than relying on pediatric herd effects exclusively. Despite similarities in vaccine-type IPD reductions, the NVT IPD trends were variable, which may have been affected by schedule, uptake, age, genetics and environment, geographic setting, and quality of surveillance, among others.