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Chemistry, Biochemistry, and PharmacologyInjury and Illness
The SARS-CoV-2 virus (the virus that causes COVID-19) has a spike protein that it uses like a tool to break into and infect cells. On its own, the spike protein is harmless and can be used as a tool to train your immune system to defend against the virus. Step 1: Scientists make copies of mRNA with instructions that tell the human body how to make only the outer spike protein of SARS-CoV-2. Step 2: mRNA is packaged inside tiny globules called lipid nanoparticles. Lipids (fatty acids) are used as the vehicle because they: Protect the mRNA from breaking down Help it pass through cell membranes and into the body's cells Step 3: The vaccine's mRNA instructions pass into muscle cells (near where a vaccine injection is given), and those muscle cells make copies of the spike protein. Step 4: Though the spikes are harmless, the body’s immune system recognizes them as antigens (foreign substances) and produces targeted antibodies to defend against them. Step 5: The body eliminates the vaccine material. Special white blood cells called memory cells "remember" the spike protein and which antibodies to make if they happen upon the spike again. Step 6: If SARS-CoV-2 (and its telltale spike proteins) enter a vaccinated person's body, the immune system reacts with antibodies that defend against infection more swiftly than it otherwise could if it had never seen the spike protein. Featured in “Pathways: Vaccine Science.”
National Institute of General Medical Sciences.
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