The present invention provides novel formulations which mitigate agitation-induced aggregation of immunogenic compositions particularly those having polysaccharide-protein conjugates. Specifically, the novel formulations comprise a poloxamer within a molecular weight range of 1100 to 17,400 which provides significant advantages over previously used surfactants including polysorbate 80. In one embodiment, the present invention provides a multivalent immunogenic composition having 15 distinct polysaccharide-protein conjugates and a poloxamer. Each conjugate consists of a capsular polysaccharide prepared from a different serotype of Streptococcus pneumoniae (1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 22F, 23F or 33F) conjugated to a carrier protein, preferably CRM197.本發明提供一種新穎調配物,其可減輕免疫原組合物(特定言之彼等具有多醣-蛋白質偶聯物者)因攪動誘發之聚集。具體而言,該等新穎調配物包含在1100至17,400之分子量範圍內的泊洛沙姆(poloxamer),泊洛沙姆提供優於先前所採用包括聚山梨醇酯80在內之表面活性劑之顯著優勢。在一個實施例中,本發明提供具有15種不同多醣-蛋白質偶聯物及泊洛沙姆之多價免疫原組合物。每一偶聯物皆由自肺炎鏈球菌(Streptococcus pneumoniae)之不同血清型(1、3、4、5、6A、6B、7F、9V、14、18C、19A、19F、22F、23F或33F)製得的莢膜多醣偶聯至載體蛋白(較佳CRM197)而組成。(無元件符號說明)