Polysaccharide and conjugate vaccines consist of highly purified, well-defined components. Their safety and batch-to-batch consistency are largely assured through physical and chemical analyses. For a typical batch of vaccine, the following tests are performed at NIBSC:

• Appearance

• endotoxin content

• molecular size determination

• polysaccharide identity and specificity

• quantification of total and unconjugated polysaccharides