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mRNA Vaccines
The Pfizer/BioNTech and Moderna vaccines for COVID-19 are mRNA vaccines. These are the first mRNA vaccines used in this many people, but scientists have studied this technology for many years.
mRNA means messenger RNA, a type of RNA, a long molecule that carries genetic instructions. It is very similar to DNA. All living things contain both DNA and RNA, except for viruses, which have either DNA or RNA.
What Messenger RNA normally does
In human cells, messenger RNA (mRNA)—a kind of RNA—normally carries copies of genetic instructions from DNA, which is stored in the nucleus. This mRNA directs the cell’s protein-making machinery to build proteins needed for growth and repair. In this way, our bodies use the genetic information we inherit from our parents to function properly.
How the COVID-19 Virus Works
The COVID-19 virus is an RNA virus. It attaches to certain cells in the human body and inserts its RNA into them. Once inside, the viral RNA takes over parts of the cell that normally create proteins from the body’s mRNA. Using the instructions in the RNA, the cell automatically starts producing proteins of new copies of the virus.
How Antibodies Protect Us
Antibodies are molecules shaped like a “Y.” They are an important part of the human immune system. These antibodies attach to viruses and other invaders and prevent them from attaching to our cells.
To understand this, imagine a door key. The virus has a “key” that allows it to attach to and infect a cell. When the right antibodies attach to this key, the virus can no longer unlock the cell. It is like putting gum on a door key, making it impossible for the key to open the door.
How Antibodies Are Normally Produced
Antibodies are produced by the immune system after a virus enters the body. Some antibodies stay in the body longer than others.
These long-lasting antibodies help protect the person from getting sick if the virus or another harmful substance enters the body again.
How mRNA Vaccines Produce Antibodies
An mRNA vaccine enters the body through an injection. Once inside, the mRNA enters human cells. The mRNA then instructs the cells to make proteins, but these proteins are only the spike proteins. The spike is the small part of the virus that allows it to attach to and infect human cells.
After the spike protein is made, the immune system recognizes it as foreign and creates antibodies against it. These antibodies will also recognize and attack the spike protein on COVID-19 viruses if they enter the body later.
In this way, the antibodies protect against COVID-19, even though they were made by the immune system only after “seeing” the spike protein from the vaccine.
mRNA Won’t Affect Your DNA
The mRNA in the vaccine does not enter the nucleus of the cell. It stays outside the nucleus, where the cell’s DNA is kept. This means the mRNA cannot reach or change the DNA.
There is misinformation on the Web claiming that mRNA can change DNA, but this is not true. After the mRNA is used to make the spike proteins, it is broken down into smaller molecules. These smaller molecules are then “recycled” to help make other molecules.
Like all mRNA in the body, the mRNA from the vaccine is broken down and used up after it has completed its job.
Summary
The vaccine uses mRNA to make only a small part of the virus—the spike protein—inside the body. This allows the immune system to create antibodies that can recognize and fight the entire virus if it ever enters the body.
Because only the spike protein is made, and not the whole virus, the vaccine cannot give anyone COVID-19.
©2021 Dr. Michael Herrera
If you are brave, you can now learn more at How mRNA vaccines work.