New antigens also typically require novel cell substrates. Vaccines are manufactured using a wide range of cell substrates (e.g., mammalian, insect, microbial, and fungal cell lines). So, vaccine products are more likely to retain their commercial value. They also are more difficult to develop and manufacture than many other biologics and thus are more difficult to make in “generic” form. They are typically administered to healthy individuals (prophylaxis), whereas other therapies are given to persons with medical conditions. Although vaccines are biological products derived from living organisms, they are more complex than many traditional therapeutics, both in terms of their components and the technologies required to produce them. They are produced through multiple steps of production and formulation for which the end product (vaccine or combination vaccine) is often a combination of many component products (antigens or vaccines). Vaccines are large, complex often hybrid biological molecules.
