Graphic from the World Health Organization describing the main<unk>  typically in vaccines. A vaccine dose contains many<unk> , very little of which is the active<unk>  the immunogen. A single dose may have merely nanograms of virus particles, or micrograms of bacterial polysaccharides. A vaccine injection, oral drops or nasal spray is mostly water. Other<unk>  are added to boost the immune response, to ensure safety or help with storage, and a tiny amount of material is left-over from the manufacturing process. Very rarely, these materials can cause an allergic reaction in people who are very sensitive to them.
Vaccine ingredients
Animal vaccination
Vaccine cooler
Cancer vaccine
Autogenous vaccines
Vaccine storage
Specific-pathogen-free
Animal products in pharmaceuticals