Differences in the avidity of antibodies evoked by four different pneumococcal conjugate vaccines in early childhood

Avidity of antibodies to Streptococcus pneumoniae type 6B, 14, 19F and 23F polysaccharides (PS) evoked by four different pneumococcal conjugate vaccin es was compared. Infants were primed with pneumococcal PS conjugated to the variant diphtheria toxin CRM197 (PncCRM), diphtheria toroid (PncD), tetanu s toroid (PncT) or meningococcal protein complex (PncOMPC) and boosted with the homologous conjugate or PS vaccine. No booster was given to children i n the PncOMPC group. Relative antibody avidity was measured by thiocyanate EIA. No vaccine specific differences were found in avidity of anti-14 or -1 9F antibodies. By contrast, antibody avidity to GB and 23F differed signifi cantly between the vaccine groups, PncCRM and PncT inducing antibodies of h ighest avidity. (C) 1999 Elsevier Science Ltd. All rights reserved.