Format

Send to

Choose Destination
J Clin Microbiol. 2019 Jan 16. pii: JCM.01766-18. doi: 10.1128/JCM.01766-18. [Epub ahead of print]

Vaccination of Icelandic children with the 10-valent pneumococcal vaccine leads to a significant herd effect among adults in Iceland.

Author information

1
University of Iceland, Faculty of Medicine, Reykjavík, Iceland.
2
Landspitali, University Hospital, Reykjavík, Iceland.
3
BioMedical Centre of the University of Iceland, Reykjavik, Iceland.
4
Parasites and Microbes, Wellcome Sanger Institute, Hinxton, United Kingdom.
5
University of Iceland, Department of Mathematics, Reykjavik, Iceland.
6
Children's Hospital Iceland, Reykjavík, Iceland.
7
Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom.
8
Department of Medicine, Imperial College London, London, United Kingdom.
9
University of Iceland, Faculty of Medicine, Reykjavík, Iceland karl@landspitali.is.

Abstract

The introduction of pneumococcal conjugate vaccines (PCV) into childhood vaccination programs has reduced carriage of vaccine serotypes and pneumococcal disease. The 10-valent PCV was introduced in Iceland in 2011. The aim of this study was to determine PCV impact on the prevalence of serotypes, genetic lineages and antimicrobial-resistant pneumococci isolated from the lower respiratory tract (LRT) of adults.Pneumococci isolated during 2009-2017 at the Landspitali University Hospital, were included (n=797). The hospital serves almost three-quarters of the Icelandic population. Isolates were serotyped and tested for antimicrobial susceptibility, and the genome of every other isolate from 2009-2014 was sequenced (n=275). Serotypes and multilocus sequence types (STs) were extracted from the genome data. Three study periods were defined: 2009-2011 (PreVac), 2012-2014 (PostVac-I) and 2015-2017 (PostVac-II).The total number of isolates and vaccine-type (VT) pneumococci decreased from PreVac to PostVac-II (n=314 vs n=230; p=0.002 and n=170 vs n=33; p<0.001, respectively), but nonvaccine-type (NVT) pneumococci increased among adults 18-64 years old (n=56 vs n=114; p=0.008). Serotype 19F decreased in the PostVac-II period: these isolates were all multidrug-resistant (MDR) and were members of the Taiwan19F-14 PMEN lineage. Serotype 6A decreased among adults ≥65 years old PostVac-II (p=0.037), while serotype 6C increased (p=0.021) and most serotype 6C isolates were MDR. Non-encapsulated S. pneumoniae (NESp) increased among adults 18-64 years old PostVac-II and the majority were MDR (p=0.028).An overall reduction in the number of LRT samples, pneumococcal-positive cultures, and significant changes in the serotype distribution became evident within four years thereby demonstrating a significant herd effect.

PMID:
30651396
DOI:
10.1128/JCM.01766-18
Free full text

Supplemental Content

Full text links

Icon for HighWire
Loading ...
Support Center