A clinical trial examining the effect of increased total CRM197 carrier protein dose on the antibody response to Haemophilus influenzae type b CRM197 conjugate vaccine

CRM197 is a carrier protein in certain conjugate vaccines. When multiple conjugate vaccines with the same carrier protein are administered simultaneously, reduced response to vaccines and/or antigens related to the carrier protein may occur. This study examined responses of infants who, in addition to diphtheria toxoid/tetanus toxoid/acellular pertussis vaccine (DTaP) received either diphtheria CRM197-based Haemophilus influenzae type b conjugate vaccine (HbOC) or HbOC and a diphtheria CRM197-based combination 9-valent pneumococcal conjugate vaccine/meningococcal group C conjugate vaccine. Administration of conjugate vaccines with CRM197 carrier protein load >50 μg did not reduce response to CRM197 conjugate vaccines or immunogenicity to immunologically cross-reactive diphtheria toxoid.