Invasive Pneumococcal Disease Caused by Nonvaccine Serotypes Among Alaska Native Children With High Levels of 7-Valent Pneumococcal Conjugate Vaccine Coverage

Abstract

Before introduction of 7-valent pneumococcal conjugate vaccine (PCV7), Alaska Native children and adults experienced an excess burden of invasive pneumococcal disease (IPD) compared with non–Native Alaskans.¹ The greatest disparity in IPD was among children younger than 2 years for whom the annualized rate (450/100 000 per year) was 3 times higher than for non–Native Alaskan children younger than 2 years who have rates similar to the overall US population.^1,2 Introduction of PCV7 into the routine childhood vaccination schedule resulted in decreases in vaccine-type IPD and consequent decreases in all IPD among US children.^3-8 7-Valent pneumococcal conjugate vaccine was licensed in February 2000 and introduced into the routine childhood vaccine schedule for all Alaskan children on January 1, 2001.⁹ In the first 3 years after PCV7 introduction, vaccine-type IPD rates (from 1995-2000 to 2001-2003) decreased by 91% and total IPD rates decreased by 65% among Alaska Native children younger than 2 years.¹⁰ Additionally, PCV7-type Streptococcus pneumoniae nasopharyngeal colonization declined in rural Alaska Native children and adults, whereas the overall rate of S pneumoniae colonization remained unchanged.^10,11