The impact of vaccination with conjugated pneumococcal vaccine on pneumococcal carriage and disease caused by pneumococci in Icelandic children

• Main Author: Sigurdsson, Samuel
• Other Authors: Ásgeir Haraldsson, Læknadeild (HÍ), Faculty of Medicine (UI), Heilbrigðisvísindasvið (HÍ), School of Health Sciences (UI), Háskóli Íslands, University of Iceland
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: University of Iceland, School of Health Sciences, Faculty of Medicine 2018
• Subjects: Pneumococcal vaccination; Acute otitis media; Pneumococcal carriage; Pneumonia; Invasive pneumococcal disease; Bólusetningar; Nefkok; Eyrnabólga; Lungnabólga; Faraldsfræði; Háls-; nef- og eyrnasjúkdómar; Læknisfræði; Doktorsritgerðir; Reykjavík; Iceland
• Online Access: https://hdl.handle.net/20.500.11815/1187

Pneumococci are commonly carried asymptomatically in the nasopharynx, especially in children. Pneumococci are also one of the major bacterial pathogens causing both severe infections and non-severe infections in both children and adults. The most severe infections are invasive pneumococcal diseases (IPD) being one of the leading causes of mortality and morbidity worldwide. Additionally, pneumococci are among the most common bacterial pathogens causing pneumonia and acute otitis media (AOM) and the most common indication for antimicrobial prescriptions in young children. The aims of the study were to investigate the possible changes in the carriage and serotypes of pneumococci in the nasopharynx of children attending day care centres and evaluate the change in the epidemiology of paediatric pneumococcal infections following the introduction of the pneumococcal nontypable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) in Iceland in 2011. Around 500 samples were collected yearly from 2009 to 2015, from healthy children two to six years of age, attending 15 day care centres in the Reykjavík, capital area. Samples were inoculated and incubated within four to six hours of sampling using methods maximizing pneumococcal detection. All pneumococcal isolates were serotyped using latex agglutination and PCR. Antimicrobial susceptibility was determined for five common antimicrobials using the 2012 EUCAST methods and criteria. Direct impact was evaluated comparing children born prior to the initiation of the vaccination (vaccine not eligible cohort, VNEC) with children born after the vaccination (vaccine eligible cohort, VEC). The herd impact was evaluated by comparing samples collected from older non-vaccinated children before and after the start of the vaccination. The impact on primary care visits due to AOM was evaluated by following every child born in Iceland from 2005 to 2015 until three years of age or end of the study period. Using unique social security numbers linked to patients’ records allowed the ...