To the Editor.
—The recent article by Clemens et al1 states the need for care when assessing potential interference in combination of or even simultaneous administration of pediatric vaccines. Their data showed reductions in the response to pertussis antigens, especially when diphtheria-tetanus-pertussis (DTP) and polyribosylribitol phosphate polysaccharide tetanus toxoid (PRP-T) are combined, and are in concert with the reduced response to the PRP-T in the combined vaccine shown by Ferreccio et al.2However, these conclusions cannot be generalized to other combinations of DTP and Haemophilus influenzae type b conjugates since the Haemophilus components are different.We have studied the effect of HibTITER (HbOC; diphtheria CRM197 oligosaccharide conjugate vaccine) on the response of infants in the United States at 7 months to each of the components of DTP after vaccination at 2,4, and 6 months of age. The data showed no effect of simultaneous administration of DTP and
Paradiso PR. Combined Childhood Immunizations. JAMA. 1992;268(13):1685. doi:10.1001/jama.1992.03490130073028