Impacts of Catch-Up Immunization program with the 13-Valent pneumococcal Conjugate vaccine in Taiwan: Focus on age-stratified differences and high-risk population (2001–2015)

Abstract

BackgroundTaiwan commenced a national catch-up immunization program with a 13-valent pneumococcal conjugate vaccine (PCV13) in 2013 for children aged 2–5 years old and in 2014 for children aged 1–5 years old. However, real-world nationwide evidence of both the direct protection and indirect protection of all-cause pneumonia and pneumococcal pneumonia has been scarce, especially among high-risk populations, defined as patients with chronic diseases or immunosuppression. The aim of this study was to examine the impact of the national PCV13 catch-up program on all-cause pneumonia and pneumococcal pneumonia among overall and high-risk populations using interrupted time series analysis. MethodsUsing the National Health Insurance Research Database (NHIRD) from January 2001 to December 2015, we assessed the impact of this catch-up program by interrupted time-series analyses age-stratified (0–1, 2–4, 5–9, 10–17, 18–34, 35–49, 50–64, 65 + years old) incidence of pneumococcal pneumonia and all-cause pneumonia (100,000 person-quarter) among the overall and high-risk populations. ResultsThe impact of this program was most profound on the incidence of pneumococcal pneumonia in children aged 2–4 years old (level change −10.56 per 100,000 person-quarters, p = 0.04; trend change −2.93, p less than 0.01). Indirect protection among unvaccinated children (0–1 years old: trend change −1.19, p = 0.01; 5–9 years old: trend change −1.04, p = 0.03; 10–17 years old: level change −1.42 per 100,000 person-quarters, p = 0.03) was also found. The incidence of all-cause pneumonia also decreased in children aged 2–4 (level change −234.91 per 100,000 person-quarter, p = 0.058) and 5–9 years old (level change −173.96 per 100,000 person-quarter, p = 0.0424). However, we did not find a significant impact among most high-risk populations. ConclusionsOur study suggests that the introduction of this catch-up program with PCV13 was associated with significant declines in the incidence of pneumococcal pneumonia and all-cause pneumonia in vaccinated children, and indirect protection from the program was also found in unvaccinated children.