While the majority of vaccinations include an infectious pathogen or a portion thereof, mRNA vaccines give the genetic instructions necessary for human cells to produce viral or bacterial proteins. Our immune system reacts to these stimuli and develops immunity.
Messenger RNA (mRNA) is a naturally occurring single-stranded molecule found in all of our cells. It transports the instructions for protein synthesis from our genes in the cell nucleus to the cytoplasm, the cell’s major body.
The cytoplasmic enzymes then translate the information contained in mRNA and synthesize proteins.
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An mRNA vaccine instructs human cells to produce a bacterial or viral protein. Our immune system then responds to these proteins and creates the capabilities necessary to combat future pathogen infections.
Although mRNA vaccine technology is not novel, there were no mRNA vaccines approved for human use until recently.
What makes mRNA vaccines unique?
Certain vaccinations employ a whole virus or bacterium to instruct our systems on how to develop protection against the disease. These pathogens have been rendered inactive or attenuated, which implies that they have been weakened. Other vaccinations are composed of virus or bacterium fragments.
The recombinant vaccine technique makes many copies of a certain viral or bacterial protein or, in some cases, a tiny portion of the protein using yeast or bacterial cells.
mRNA vaccines do not require this step. They are chemically manufactured without the need for cells or pathogens, which simplifies the manufacturing process. mRNA vaccines include the information necessary for our own cells to synthesize the pathogen’s proteins or protein fragments.
Notably, mRNA vaccines include just the information necessary to create a tiny portion of a pathogen. Our cells cannot synthesize the entire pathogen based on this knowledge.
Both the mRNA COVID-19 vaccines produced by Pfizer/BioNTech and Moderna are incapable of causing COVID-19. They do not have all of the information necessary for our cells to produce the SARS-CoV-2 virus and hence cannot induce infection.
While the notion of mRNA vaccines may appear straightforward, the technology is rather complicated.
Stability and safety concerns
RNA is a molecule that is infamous for its fragility. Successfully delivering mRNA to cells within our bodies and ensuring that it is not degraded by enzymes within our cells are critical problems in vaccine development.
Chemical changes made throughout the production process can increase the stability of mRNA vaccines substantially.
Encapsulating mRNA in lipid nanoparticles is one method of ensuring that a vaccine enters cells and successfully delivers the mRNA to the cytoplasm.
mRNA does not persist in our cells for an extended period of time. Once it has sent its instructions to our cells’ protein-making machinery, mRNA is degraded by enzymes called ribonucleases (RNases).
mRNA cannot reach the nucleus of a cell because it lacks the signals necessary to do so. This indicates that RNA cannot be integrated into the vaccinated cell’s DNA.
With mRNA vaccinations, there is no risk of long-term genetic alterations.
Pfizer and Moderna have conducted safety testing on their mRNA COVID-19 vaccines in human clinical trials.
After analyzing safety data from over 37,000 trial participants, the United States Food and Drug Administration (FDA) granted Emergency Use Authorization (EUA) for the Pfizer mRNA vaccine.
The FDA stated that the most frequently reported adverse effects, which generally lasted several days, were discomfort at the injection site, fatigue, headache, muscular soreness, chills, joint pain, and fever. “Notably, more persons had these adverse effects following the second dosage than following the first dose, indicating that vaccination providers and receivers should anticipate some side effects following either dose, but especially following the second dose.”