How do babies’ immune systems respond to pneumococcal conjugate vaccine?
Ly-Mee Yu with Penny Salt, Sarah Oh, Andy Pollard (Oxford) and members of the Oxford Vaccine Group
Worldwide there is significant morbidity and mortality associated with pneumococcal infection. In January 2002, a heptavalent pneumococcal protein-polysaccharide conjugate vaccine was licensed in the United Kingdom for children at high risk of developing severe disease aged 2 months to 5 years of age. The polysaccharide capsule of Streptococcus pneumoniae (SP) is its primary virulence factor by enabling the organism to resist phagocytosis by granulocytes and macrophages.
The primary aim of this study is to examine the relative role of nasopharyngeal carriage of SP in priming the infant immune response to pneumococcal polysaccharide antigens. In specific, following vaccination, to explore whether antibody level and avidity of antibody is higher in children who have risk factors for carriage. High avidity in children with siblings and who attend day-care and low avidity in serum of children without sibling and who do not attend day-care would suggest immunological priming through carriage in the first group. Target sample size was 160 infants.
