mRNA vaccines are a new type of vaccine that use a molecule called messenger RNA (mRNA) to produce an immune response. Instead of introducing a weakened or dead virus into the body like traditional vaccines, mRNA vaccines deliver genetic instructions (mRNA) into cells. These instructions tell the cells to produce a harmless piece of a protein that is found on the surface of a virus, such as the spike protein of the SARS-CoV-2 virus that causes COVID-19. Once the protein piece is made by the cells, it triggers the immune system to recognize it as foreign and produce antibodies and activate immune cells. This trains the immune system to recognize and fight the actual virus if the person is exposed to it in the future, without ever having been infected by the virus itself. The mRNA from the vaccine does not enter the nucleus of the cells where DNA is stored, so it cannot alter a person's DNA. After the protein is made, the mRNA is quickly broken down by the cells. Advantages of mRNA vaccines include their rapid design and production, ability to induce a strong immune response, and safety. mRNA vaccines became widely known with the Pfizer-BioNTech and Moderna COVID-19 vaccines, which were authorized in 2020. Researchers have been studying mRNA vaccine technology for decades and are exploring its application for other diseases as well. In summary, mRNA vaccines:

• Use mRNA to instruct cells to make a viral protein
• Trigger an immune response without using live virus
• Do not alter DNA
• Train the immune system to recognize and fight the virus
• Can be developed and produced faster than traditional vaccines

They have been primarily used against COVID-19 so far, with ongoing research into other uses. This explanation is based on consolidated findings from sources including Wikipedia, CDC, MedlinePlus, and health authorities.