RESPONSE TO A HEPTAVALENT CONJUGATE STREPTOCOCCUS-PNEUMONIAE VACCINE IN CHILDREN WITH RECURRENT INFECTIONS WHO ARE UNRESPONSIVE TO THE POLYSACCHARIDE VACCINE

Objective, To determine whether children with recurrent respiratory in fections who failed to respond to the conventional polysaccharide vacc ine would respond to a pneumococcal conjugate vaccine. Methods. Childr en referred to our clinic for recurrent respiratory infections who had no known primary or secondary immunodeficiencies mere immunized with a 23-valent pneumococcal polysaccharide vaccine. IgG antibodies to pne umococcal serotypes 1, 3, 4, 6B, 9V, 14, 18C, 19F and 23F were determi ned by enzyme-linked immunosorbent assay before and 4 to 6 weeks after immunization. An adequate IgG antibody response to an individual sero type was arbitrarily defined as a postimmunization antibody titer grea ter than or equal to 1.3 mu g/ml Or at least 4 times the preimmunizati on value. Immunization with an experimental CRM197-heptavalent pneumoc occal conjugate vaccine was offered to patients without an adequate re sponse to 4 or more vaccine serotypes (nonresponders). Post-conjugate immunization antibody concentrations were measured 4 to 6 weeks later. Results. In nonresponder patients (n = 17) geometric mean post-conjug ate immunization (C) serum antibody concentrations (mu g/ml) compared with post-polysaccharide (PS) concentrations were: (serotype, C vs, PS ) 4, 1.11 vs. 0.30 (P = 0.000227); 6B, 0.46 vs, 0.20 (P = 0.017267); 9 V, 0.82 vs. 0.29 (P = 0.002163); 14, 1.88 vs. 0.27 (P = 0.000615); 18C , 0.98 us, 0.32 (P = 0.021962); 19F, 1.24 vs. 0.34 (P = 0.002844); and 23F, 0.87 us. 0.16 (P = 0.000194), In responder patients (n = 67), af ter 1 dose of the polysaccharide vaccine, geometric mean antibody conc entrations were: 4, 1.05; 6B, 0.96; 9V, 1.55; 14, 1.65; 18C, 1.62; 19F , 1.30; and 23F, 1.02, Conclusions. Our results show that a pneumococc al conjugate vaccine is capable of inducing an IgG response in patient s with recurrent infections who had failed to mount an adequate respon se to the polysaccharide vaccine. Conjugate vaccines may be of value i n the management of children with recurrent pneumococcal respiratory i nfections.