What is the mechanism of action for mRNA vaccines?

mRNA vaccines work by providing cells with the genetic code needed to produce a harmless piece of a virus, specifically the spike protein found on the surface of the virus responsible for a specific disease, such as SARS-CoV-2 for COVID-19. This process starts when the mRNA from the vaccine is taken up by the cells in the body. Once inside, the cells use the information encoded in the mRNA to synthesize the spike protein.

This spike protein is harmless on its own and does not cause disease. However, its presence prompts the immune system to recognize it as a foreign entity. This immune response leads the body to produce antibodies and train immune cells to recognize and respond to the actual virus if it is encountered in the future. Thus, by using this genetic code to stimulate a response, mRNA vaccines effectively prepare the immune system to fight off the real virus, establishing an immune memory without exposing the individual to the virus itself.

This mechanism illustrates the innovative approach of mRNA technology in vaccine development, which contrasts sharply with traditional vaccines that may use live attenuated viruses, killed viruses, or inactivated components of pathogens.