Carrier-induced epitopic suppression is of particular concern where multipleconjugates with the same carrier proteinare administered simultaneously. To avoid the suppression, the inventionminimises the amount of unconjugated carrier protein in avaccine. The invention provides a composition for immunising a patient againsta disease caused by Neisseria meningitidis, wherein(1) the composition comprises conjugates for at least two of the fourmeningococcal serogroups A, C, W135 and Y, where at leasttwo of the conjugates have a common carrier protein； and (2) the compositionincludes the common carrier in an unconjugated format less than 10 µg/ml.
