Impact of 13-Valent Pneumococcal Conjugate Vaccine on Colonization and Invasive Disease in Cambodian Children

• Published in: Clinical infectious diseases Vol. 70; no. 8; pp. 1580 - 1588
• Main Authors: Turner, Paul, Leab, Phana, Ly, Sokeng, Sao, Sena, Miliya, Thyl, Heffelfinger, James D, Batmunkh, Nyambat, Lessa, Fernanda C, Walldorf, Jenny A, Hyde, Terri B, Ork, Vichit, Hossain, Md Shafiqul, Gould, Katherine A, Hinds, Jason, Cooper, Ben S, Ngoun, Chanpheaktra, Turner, Claudia, Day, Nicholas P J
• Format: Journal Article
• Language: English
• Published: US Oxford University Press 10-04-2020
• Subjects: and Commentaries; Asian People; Cambodia - epidemiology; Child; Child, Preschool; Heptavalent Pneumococcal Conjugate Vaccine; Humans; Infant; Pneumococcal Infections - epidemiology; Pneumococcal Infections - prevention & control; Pneumococcal Vaccines; Serogroup; Vaccines, Conjugate; Cambodia; vaccine; Cambodia; colonization; children; Streptococcus pneumoniae
• ISSN: 1058-4838; 1537-6591
• DOI: 10.1093/cid/ciz481

Abstract
Background
Cambodia introduced the 13-valent pneumococcal conjugate vaccine (PCV13) in January 2015 using a 3 + 0 dosing schedule and no catch-up campaign. We investigated the effects of this introduction on pneumococcal colonization and invasive disease in children aged <5 years.
Methods
There were 6 colonization surveys done between January 2014 and January 2018 in children attending the outpatient department of a nongovernmental pediatric hospital in Siem Reap. Nasopharyngeal swabs were analyzed by phenotypic and genotypic methods to detect pneumococcal serotypes and antimicrobial resistance. Invasive pneumococcal disease (IPD) data for January 2012–December 2018 were retrieved from hospital databases. Pre-PCV IPD data and pre-/post-PCV colonization data were modelled to estimate vaccine effectiveness (VE).
Results
Comparing 2014 with 2016–2018, and using adjusted prevalence ratios, VE estimates for colonization were 16.6% (95% confidence interval [CI] 10.6–21.8) for all pneumococci and 39.2% (95% CI 26.7–46.1) for vaccine serotype (VT) pneumococci. There was a 26.0% (95% CI 17.7–33.0) decrease in multidrug-resistant pneumococcal colonization. The IPD incidence was estimated to have declined by 26.4% (95% CI 14.4–35.8) by 2018, with a decrease of 36.3% (95% CI 23.8–46.9) for VT IPD and an increase of 101.4% (95% CI 62.0–145.4) for non-VT IPD.
Conclusions
Following PCV13 introduction into the Cambodian immunization schedule, there have been declines in VT pneumococcal colonization and disease in children aged <5 years. Modelling of dominant serotype colonization data produced plausible VE estimates.
The introduction of the 13-valent pneumococcal conjugate vaccine into Cambodia has led to declines in vaccine-type and antimicrobial-resistant pneumococcal colonization and disease in young children. The inclusion of multiple-serotype colonization data did not significantly alter vaccine effectiveness estimates.