False. mRNA stands for “messenger ribonucleic acid” and are instructions for cells to make a protein or a piece of a protein. The mRNA from two-dose COVID-19 mRNA vaccines (such as Pfizer and Moderna) never enters the nucleus of a cell, which is where our DNA is kept. This means the mRNA does not affect or interact with our DNA in any way. Instead, COVID-19 vaccines that use mRNA work with the body’s immune system to safely develop protection (immunity) to disease.
Additionally, a virus replicates by pushing RNA into your cells, which prompts your cells to make new virus particles. This means that your cells have seen plenty of outside RNA during your life, including anytime you get a head cold or an RNA viral infection like chickenpox. Learn more about how COVID-19 mRNA vaccines work.
Here’s an infographic from MDHHS that helps to clarify how MRNA vaccines provide immunity against the virus causing COVID-19 (click to enlarge):
The one-dose Johnson & Johnson vaccine authorized for emergency use in the United States is known as an adenovirus vector vaccine. This type of vaccine uses a modified version of a different and harmless virus as a vehicle to deliver genetic instructions to a cell. These instructions trigger our immune system to begin producing antibodies and activating other immune cells to fight off what it thinks is an infection.
At the end of the process, our bodies have learned how to protect us against future infection with the virus that causes COVID-19. The benefit is that we get this protection without ever having to risk the serious consequences of infection.
This type of vaccine does not cause infection with either COVID-19 or the virus that is used as the vector. The genetic material delivered by the viral vector does not integrate into a person’s DNA. Vaccines of this type have been well-studied in clinical trials, and viral vector vaccines have been used to respond to recent Ebola outbreaks.