Pneumococcal Conjugate Vaccine Followup

Recently, controversy has emerged regarding the role of the 23vPPV in infants due to potential immunological hypo-responsiveness (i.e. a poorer immune response to repeat vaccination). Although previous experience of 23vPPV in children in PNG has demonstrated protective efficacy against acute lower respiratory tract infection, the investigators feel it is a matter of urgency to determine if 23vPPV administration provides elevated antibody concentrations at 3 to 5 years of age, and to ensure the immunological safety of the 23vPPV in infants. Following consent and eligibility assessment, a baseline blood sample and nose swab will be taken, a 0.1ml dose of 23vPPV will be administered and a follow up blood sample and nose swab will be collected 28 days later. The investigators will also collect data on incidence of ALRI in all study participants by medical record review.