ARE THE NEW COMBINED VACCINES EFFICACIOUS

The combination vaccines are very useful to reduce the number of conta cts required to immunize a child fully and to improve the vaccine cove rage. Recently the new combinations between Haemophilus Influenzae vac cine (PRP-T) and pertussis vaccines in D-T-P (IVP) combined vaccines h ave suggested interferences with immunogenicity for PRP-T vaccines. Th e interference for pertussis antibodies is not significative. The depr ession of antiPRP antibodies is shown with the whole-cell pertussis va ccine, but the level of antibodies is related to a good protective eff icacy. Inversely, when PRP-T vaccine is combined with acellular pertus sis vaccines, the antibodies levels are lower, especially the number o f children with a level higher than 1 mcg/ml. At the present time, the se combinations between PRP-T vaccines and acellular pertussis vaccine s are not recommended for primary immunization in infants in France. S uch constatations emphasize the necessity to perform wide comparative trials to test immunogenicity for all the ne.ut combinations between o ld and new vaccines. A decrease in immunogenicity of combination vacci nes is acceptable as long as protective efficacy is preserved. It is p ossible that the growing number of new, vaccines to combine will be li mited to keep a clinical efficacy.