Viral vaccines

Viral antigens and immune responses

An antigen is an element recognised by the immune system. In vaccination it participates in a specific response and immune memory mechanisms. That principle differs from an antiviral directed at a stage of viral multiplication. The disease or virus name alone does not define the technology used in a preparation. Antibodies, immune cells and their responses must also not be reduced to one uniform property of every vaccine or an individual promise of protection. The antigen provides a specific biological target while the complete preparation retains its own pharmaceutical characteristics.

Technologies and formulations

Live attenuated and inactivated vaccines differ in the nature of their preparation. Subunit vaccines contain selected antigenic components, while other approaches use messenger RNA, for example, to produce an antigen. These examples describe technological principles rather than a list of products assumed to be present in the catalogue. Adjuvants and excipients have functions different from antigens. Viral alone therefore does not establish the components, conditions of use or storage profile of a particular medicinal product, even when another vaccine concerns the same infectious agent or disease.

Valencies, strains and routes

A vaccine can combine several antigens or viral types according to composition. Combinations against several diseases and preparations targeting several types of one agent cannot be described by a number alone. For selected vaccines, strain composition can change according to seasonal recommendations and then contributes to the identity of the relevant formulation. Injectable, oral and nasal presentations have product-specific characteristics. A vial, prefilled syringe or powder with solvent does not automatically identify the same route or preparation state. Complete composition and presentation give those familiar packaging terms their precise pharmaceutical meaning.

Frequently asked questions