An mRNA vaccine is a type of vaccine that uses a synthetic copy of a molecule called messenger RNA (mRNA) to produce an immune response. Unlike traditional vaccines that introduce weakened or inactivated viruses or parts of viruses into the body, mRNA vaccines deliver the genetic instructions (mRNA) for making a specific viral protein—usually a harmless piece such as the spike protein found on the virus's surface—into cells. Here's how it works:
- The mRNA in the vaccine is taken up by cells, which use their internal machinery to read the instructions and produce the viral protein.
- This protein is then displayed on the cell surface, where the immune system recognizes it as foreign and triggers an immune response.
- The immune system produces antibodies and activates other immune cells to recognize and fight the real virus if the vaccinated person is exposed later.
- The mRNA itself is quickly broken down and does not enter or alter the cell's DNA.
mRNA vaccines can be designed and produced relatively quickly and at lower cost compared to traditional vaccines. They induce both cellular and humoral immunity (antibody response). The Pfizer–BioNTech and Moderna COVID-19 vaccines are prominent examples of mRNA vaccines approved for emergency use and widespread vaccination campaigns. In summary, mRNA vaccines teach the body to make a piece of a virus to trigger an immune response without using the live virus, preparing the immune system to fight the virus if encountered in the future.
