Historical Population-Level Impact of Infant 13-Valent Pneumococcal Conjugate Vaccine (PCV13) National Immunization Programs on Invasive Pneumococcal Disease in Australia, Canada, England and Wales, Israel, and the United States

Abstract

Introduction: This study estimates the annual population-level impact of 13-valent pneumococcal conjugate vaccine (PCV13) infant national immunization programs (NIPs) on vaccine-type and non-vaccine type invasive pneumococcal disease (IPD) incidence across all ages using national surveillance data.

Methods: We identified countries (Australia, Canada, England and Wales, Israel, and the US) with national IPD active surveillance data that introduced the seven-valent PCV (PCV7) followed by PCV13, which also reported annual serotype- and age group-specific incidence. We extracted IPD incidence by serotype groupings [PCV13 minus PCV7 (PCV13-7) serotypes; PCV13-7 serotypes excluding serotype 3; non-PCV13 serotypes; and the 20-valent (PCV20) minus PCV13 (PCV20-13) serotypes] and by age groups (< 2 years, 2-4 years, 5-17 years, 18-34 years, 35-49 years, 50-64 years, and ≥ 65 years). For each country, we calculated the annual relative change in IPD incidence (percent change), and the corresponding incidence rate ratio (IRR), for 7 years post introduction compared to the year prior to PCV13 program initiation.

Results: PCV13-7 vaccine-type IPD incidence consistently decreased over time following introduction of PCV13 across countries, reaching an approximate steady state after 3-4 years in ages < 5 years, with roughly 60-90% decrease (IRRs = 0.1-0.4) and after 4-5 years in ages ≥ 65 years with approximately 60-80% decrease (IRRs = 0.2-0.4). Incidence declines were more substantial for the PCV13-7 grouping when excluding serotype 3. Non-PCV13 serotype incidence was variable by country and age group, ranging from virtually no serotype replacement compared to the PCV7 period across ages in the US to increases for other countries ranging from 10 to 204% (IRRs = 1.10-3.04) in children < 5 years and 41% to 123% (IRRs = 1.41-2.23) in ages ≥ 65 years.

Conclusions: Countries with longstanding PCV13 infant NIPs have observed substantial direct and indirect benefits, which are demonstrated in this study by the reduction in PCV13-7 IPD incidence compared to PCV7 period in all age groups. Over time, non-PCV13 serotypes have emerged in response to the reduction of incidence of PCV13-unique serotypes. Higher-valent PCVs are needed to address this emerging pneumococcal disease burden as well as the direct vaccination of both pediatric and adult populations against the most prevalent circulating serotypes.

Keywords: Indirect effects; PCV13; PCV20; Pneumococcal disease; Pneumococcal vaccination; Public health impact; Retrospective analysis; Serotype replacement; Vaccine impact.

Fig. 1

PCV13- PCV7 serotypes (serotypes 1, 5, 7F, 3, 6A, 19A). PCV pneumococcal conjugate vaccine; UK England and Wales; US United States. PCV7 is the 7-valent PCV; PCV13 is the 13-valent PCV. Incidence rate ratios calculated as Incidence_x/Incidence₀, where x represents the years since PCV13 was introduced and 0 represents the year prior to PCV13 introduction. The figures present the percentage incidence change and incidence rate ratios for age groups < 2 (A), 2–4 (B), 5–17 (C), 18–34 (D), 35–49 (E), 50–64 (F), and ≥ 65 (G)

Fig. 2

Average age-specific PCV13-7 incidence reduction among studied countries. PCV13-7 = serotypes unique to PCV13 compared to PCV7. PCV = pneumococcal conjugate vaccine

Fig. 3

Non-vaccine type serotypes. PCV = pneumococcal conjugate vaccine; UK = England and Wales; US = United States. PCV7 is the 7-valent PCV; PCV13 is the 13-valent PCV. Incidence rate ratios calculated as Incidence_x/Incidence₀, where x represents the years since PCV13 was introduced and 0 represents the year prior to PCV13 introduction. The figures present the percentage incidence change and incidence rate ratios for age groups < 2 (A), 2–4 (B), 5–17 (C), 18–34 (D), 35–49 (E), 50–64 (F) and ≥ 65 (G)