What is unique about their approach is the use of genetic material called messenger RNA, or mRNA, that was produced in a lab. No live virus per se is used. The mRNA is a genetic code that tells cells what to build — in this case, an antigen that may induce an immune response to the virus. Essentially a genetically engineered antigen.
They inject the mRNA into human cells. The cell’s machinery uses the instructions to make virus antigens that the immune system reacts to. Cells respond to the instructions as a normal part of their daily existence. This is the same trait infectious viruses exploit; they cannot reproduce on their own, so they use a cell’s machinery to make copies of themselves. They burst out of the cell and infect more cells, widening the infection.
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