Vaccines comprise a very diverse group of products with respect to chemical composition and manufacturing processes. Vaccines can also be very complex as they are frequently composed of multiple entities and administered as a combination vaccine. For instance, six or more different antigens can be included in common pediatric vaccines, and seasonal influenza vaccines are quadrivalent. Adding to that complexity, many vaccines are administered with adjuvants that may involve complex formulations and manufacturing processes. The use of adjuvants increases the challenges of developing a robust control strategy.

Vaccines are characterized by relatively long product lifecycles. Vaccines that were licensed decades ago (e.g., for tetanus and diphtheria toxoids, tuberculosis, measles, mumps, and rubella) are still produced and recommended for global vaccination programs. The manufacturing programs for these vaccines must be updated continually to comply with contemporary regulatory expectations, which requires multiple supplemental submissions around the world. These technical and regulatory challenges lead to an intricate management process for vaccine lifecycle and supply chain.