mRNA Vaccines: Introduction ? Vaccine is nothing but a biological preparation that provides active acquired immunity to a particular disease. They stimulate the body's immune system to recognize the disease-causing microorganism as a threat and destroy it. Its administration is known as vaccination, the most effective method of preventing infectious diseases. ? mRNA vaccines and therapies are used for prevention and treatment of serious health conditions such as cancer, infectious diseases such as acquired immunodeficiency syndrome (AIDS) and respiratory diseases ? mRNA vaccines have ability to mimic natural viral infections by entering cells and are used to produce viral antigen proteins from within the cell ? Multiple mRNAs that are encoded for various viral proteins can be used as a single vaccine, thereby helping production of complex multimeric antigens