Components of vaccine:

Stabilizers

Stabilizers are used to help the vaccine maintain its effectiveness during storage. Vaccine stability is essential, particularly where the cold chain is unreliable. Instability can cause loss of antigenicity and decreased infectivity of LAV. Factors affecting stability are temperature and acidity or alkalinity of the vaccine (pH) Bacterial vaccines can become unstable due to hydrolysis and aggregation of protein and  carbohydrate molecules. Stabilizing agents include MgCl2 (for OPV), MgSO4 (for measless), lactose-sorbitol and sorbitol-gelatine.