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What do we know about how an mRNA vaccine interacts with human cells?

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The human body has lots of different types of cells, and they serve many different purposes. MRNA vaccines like Pfizer and Moderna's vaccines interact with multiple types of cells once they enter the human body, including immune cells, which are the cells that launch a response to the virus and help us build immunity to COVID-19. Additionally, "T-follicular helper cells" (T cells) are a type of immune cell that is activated by the mRNA vaccine. "Germinal center B cell responses" (GC B cells) are also activated by the mRNA vaccine.  mRNA vaccines also interact with dendritic cells. Dendritic cells help our bodies with transporting foreign invaders, like a virus or a vaccine, to the body's immune-boosting T cells, so that we can build up immunity to that foreign invader. Lastly, the mRNA vaccines also interact with cells in our muscles when the vaccine is injected.

This article was published on
January 5, 2021

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The human body has lots of different types of cells, and they serve many different purposes. MRNA vaccines like Pfizer and Moderna's vaccines interact with multiple types of cells once they enter the human body, including immune cells, which are the cells that launch a response to the virus and help us build immunity to COVID-19.

Additionally, "T-follicular helper cells" (T cells) are a type of immune cell that is activated by the mRNA vaccine. "Germinal center B cell responses" (GC B cells) are also activated by the mRNA vaccine. 

mRNA vaccines also interact with dendritic cells. Dendritic cells help our bodies with transporting foreign invaders, like a virus or a vaccine, to the body's immune-boosting T cells, so that we can build up immunity to that foreign invader. Lastly, the mRNA vaccines also interact with cells in our muscles when the vaccine is injected.

Context and background

There are three primary types of mRNA vaccines: non-replicating mRNA vaccines, in vivo self-replicating mRNA vaccines, and in vivo dendritic cell non-replicating mRNA vaccines. 

A non-replicating mRNA vaccine is the simplest type of an mRNA vaccine in which a strand of messenger RNA (mRNA) is packaged and delivered to the body to be taken up by specific cells to make proteins and trigger an immune response.

An in vivo self-replicating (also known as self-amplifying) mRNA vaccine is a bit more complex. It packages the strand of mRNA with other RNA to help make sure that it will be copied once inside the specific cell. This approach allows greater quantities of the antigen to be produced from a smaller quantity of vaccine.

An in vivo dendritic cell non-replicating mRNA vaccine is carried out by taking dendritic cells from a patient’s blood, transfecting (introducing genetic material to) those cells with the vaccine, and injecting those cells back into a person to stimulate an immune response.

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