Vaccines and other biological medicines are derived from living materials. This poses particular problems with regard to assuring their efficacy and safety due to the inherent variability of starting materials, the production processes, and the complex nature of the products themselves. For vaccines and other biological medicines, the key to effective quality control (QC) is rigorous testing and validation applied to the starting materials, to different stages of the production process, and also to the final products.
With the advent of molecular biotechnology, there are increasing uses of molecular methods for the characterization and QC of vaccines whether they are currently used or newly developed. The World Health Organization Expert Committee on Biological Standardization (WHO ECBS) has put an increasing emphasis on products and assays arising from new biotechnology in internationally harmonized activities of quality assurance and safety of biologicals, and of vaccines in particular.