Two newer vaccine technologies are viral vector and mRNA vaccines. They differ from other vaccines in that they don't use the antigen itself in the vaccine, but rather stimulate your cells to make the antigen which then stimulates the immune response.
In the case of viral vector vaccines, DNA from the pathogen is placed in a modified version of a different nonpathogenic virus, which is then injected into the recipient. When the virus enters the person's cells, the DNA is incorporated and instructs their cells to synthesize the pathogen's antigens which by themselves do not cause disease. Then, an immune response is activated against the newly synthesized antigens.
In mRNA vaccines, the messenger RNA of the pathogenic virus is formulated within a matrix of lipid molecules. When injected, this combination enters the person's cells and the mRNA directs the cells to synthesize the pathogen's antigens. Some of the COVID-19 vaccines are formulated this way—they instruct the cells to synthesize the spike proteins from the COVID-19 virus. The image to the right is of the COVID-19 virus. The spike proteins are colored red.
Viral vector vaccines can typically be stored in the refrigerator, but some mRNA vaccines must be frozen for longer-term storage.
