mRNA Vaccines for COVID-19. Vaccines are substances that protect you from harmful diseases. Most vaccines contain parts of weakened or dead germs that trigger your immune system to fight the disease. But mRNA vaccines for COVID-19 are different. They contain a substance, called mRNA, that teaches your cells how to make a protein that triggers an immune response. In order to understand how these vaccines work, it’s important to know what mRNA is and how it normally makes proteins your body needs. Most cells in your body have a “command center” inside them, called the nucleus. It contains genetic material, called DNA, that consists of instructions for building and maintaining your body. Proteins are one of the building blocks of your body. When a new body protein needs to be built, instructions for building it are copied from your cell’s DNA and converted into a “message,” called messenger RNA, or mRNA. Then, the mRNA travels out of the nucleus to a protein-building machine in your cell, called a ribosome. As the ribosome “reads” the “message” from the mRNA, it builds the protein your body needs. mRNA vaccines take advantage of this process to help give you immunity to COVID-19. Each vaccine contains special mRNA that provides instructions for your cells to build a harmless piece of the virus, called the spike protein. The spike protein is found on the surface of the SARS-CoV-2 coronavirus that causes COVID-19. Each piece of the mRNA from the vaccine is wrapped in a protective coating. The vaccine is given as a shot in the upper arm. In the body, the mRNA particles enter your cells. Once inside the cell, the mRNA travels to a ribosome. Using the mRNA from the vaccine, the ribosome makes only a piece of the spike protein from the virus. After making the piece of the spike protein, your cell destroys the mRNA from the vaccine. It’s important to know that the mRNA from the vaccine never enters the cell’s nucleus or changes its DNA in any way. Next, your cell presents the piece of the spike protein on its surface. This allows your immune cells to detect the protein and recognize that it doesn’t belong there. As a result, your immune cells begin making antibodies as part of an immune response to the virus. In the future, if you catch the virus, the antibodies recognize and attach to the spike protein pieces on infected cells and the spike proteins on the virus. This marks them for immediate destruction by other immune cells. Like all vaccines, the benefit of these mRNA vaccines is that they give vaccinated people protection from the virus without having to get sick with COVID-19. Most mRNA vaccines for COVID-19 require you to get a second shot within a few weeks. Sometime after getting the vaccine, you may have symptoms, such as a fever. This is normal. It means the vaccine is working to make you immune to the virus. Vaccines protect you, your family, and your community from diseases that can be dangerous, or even deadly.
