Poster Presentation Lorne Infection and Immunity 2014

Long-term impact of 23vPPS on carriage in children following a reduced dose PCV primary series in infancy (#112)

Laura K Boelsen 1 2 , Eileen M Dunne 1 , Kathryn Bright 3 , Karen Lamb 4 , Lisi Tikoduadua 5 , Fiona M Russell 1 6 , E Kim Mulholland 1 3 7 , Paul V Licciardi 1 8 , Catherine Satzke 1 9
  1. Pneumococcal Research, Murdoch Childrens Research Institute, Parkville, VIC, Australia
  2. Department of Paediatrics, The University of Melbourne, Parkville, VIC, Australia
  3. Menzies School of Health Research, Darwin, NT, Australia
  4. Clinical Epidemiology & Biostatistics Unit, Murdoch Childrens Research Institute, Parkville, VIC, Australia
  5. Ministry of Health, Suva, Fiji
  6. Centre for International Child Health, Department of Paediatrics, The University of Melbourne, Parkville, VIC, Australia
  7. London School of Hygiene & Tropical Medicine, London, United Kingdom
  8. Allergy and Immune Disorders, Murdoch Childrens Research Institute, Parkville, VIC, Australia
  9. Department of Microbiology and Immunology, Doherty Institute for Infection and Immunity, The University of Melbourne, Parkville, VIC, Australia

Streptococcus pneumoniae (the pneumococcus) is a major cause of paediatric pneumonia which remains a leading cause of death for children under five wordlwide. While pneumococcal vaccines are available, resource-poor countries face challenges in implementing a full vaccination program. Some key issues are the considerable cost and the lack of coverage provided by current vaccines against serotypes that cause significant proportions of disease in these settings.

The Fiji Pneumococcal Project (FiPP) evaluated a reduced dose pneumococcal conjugate vaccine (PCV7) primary series in infancy, followed by the 23-valent pneumococcal polysaccharide vaccine (23vPPS) at 12 months of age. Children receiving 0 or 1 PCV7 dose were given a catch-up dose at 2 years of age. Immune hyporesponsiveness was observed in children aged 18 months who were given 23vPPS, compared with those who were not. Here we assess the long-term impact of 23vPPS vaccination on carriage rates and densities of pneumococci and other common bacterial species. We also compared differences in carriage of pneumococcal serotypes, and examined differences between the two main ethnic populations.

Nasopharyngeal swabs (n=194) were collected from a subset of healthy FiPP participants now 5-7 years old. Pneumococci were identified by standard culture-based methods and serotyped by latex agglutination/Quellung. Carriage rates and densities of pneumococci, Haemophilus influenzae, Staphylococcus aureus and Moraxella catarrhalis were determined by quantitative PCR.

Preliminary analysis found there were no differences in pneumococcal carriage rates (40 vs. 52%) or vaccine-type carriage (20 vs. 17%) for 23vPPS recipients compared with non-recipients. Similar results were found for pneumococcal densities. Analysis of the impact of 23vPPS vaccination on carriage of other species is ongoing. Indigenous Fijian children had significantly higher carriage rates of pneumococci (57 vs. 14%), H. influenzae (63 vs. 24%) and M. catarrhalis (86 vs. 41%), and lower carriage of S. aureus (23 vs. 41%) compared to Indo-Fijian children.

Initial analysis shows 23vPPS receipt at 12 months has no long-term impact on pneumococcal carriage rate or density.