Learn more about mRNA and how it is used in the development of vaccines.

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Messenger RNA, or mRNA, is a type of RNA found in your cells. It carries the genetic information needed to make proteins.

mRNA has become more widely discussed during the COVID-19 pandemic because of vaccines. The COVID-19 vaccines produced by Pfizer-BioNTech and Moderna both use mRNA technology to fight COVID-19.

In December 2020, the U.S. Food and Drug Administration (FDA) issued emergency use authorization for the Pfizer and Moderna COVID-19 vaccines. They became the first-ever mRNA-based vaccines to gain regulatory authorization.

In August 2021, the FDA approved the Pfizer vaccine — making it the first mRNA vaccine ever to receive full FDA approval. The FDA later approved the Moderna vaccine.

The mRNA vaccines have been an important tool in preventing COVID-19 cases and severe outcomes like hospitalizations and deaths. But what is mRNA, and what makes vaccines that use this molecule different?

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What Is mRNA?

mRNA stands for messenger ribonucleic acid. They’re single-stranded molecules that carry genetic code from DNA in a cell’s nucleus to ribosomes, which make protein in the cells. These molecules are called messenger RNA because they carry instructions for producing proteins from one part of the cell to another.

How mRNA delivers messages in three steps:

  1. A process known as transcription makes an RNA copy of a DNA sequence for a protein.
  2. This copy, known as mRNA, moves from the nucleus (center) of the cell to the ribosomes. Ribosomes, which are located in the cell outside of the nucleus, make proteins.
  3. Ribosomes “translate” the instructions in mRNA and synthesize the protein.

How Does an mRNA Vaccine Work?

mRNA vaccines work differently than traditional vaccines because they do not use a live virus. Instead, they use mRNA created in a laboratory that corresponds to a protein, or part of a protein, from a virus. The vaccine teaches our cells how to make that protein, triggering an immune response that produces antibodies.

For COVID-19, scientists engineered a synthetic mRNA that codes for the spike protein on SARS-CoV-2 — the novel coronavirus that causes COVID-19. This is the part of the virus that helps it enter human cells. The spikes are what you see on illustrations of the SARS-CoV-2 viral particle.

The synthetic mRNA in the vaccine instructs cells in the human body to make their own viral spike protein. This triggers the immune system to make antibodies to fight the virus. Once the immune system knows how to make these antibodies, it can do it again when exposed to the spike protein.

You can think of an mRNA vaccine as sending instructions into the body on how to fight COVID-19. Once the body makes the viral proteins, the immune system learns how to destroy them. This gives your body the tools to defend against SARS-CoV-2 if you’re exposed.

Lipid nanoparticles

Lipid nanoparticles are necessary in the manufacture of mRNA vaccines. Scientists encase mRNA inside a pod made of oily lipids, which allow mRNA to more easily slide into cells.

How Are mRNA Vaccines Different Than Traditional Vaccines?

The goal of any vaccine is to train your body to recognize and fight germs by producing antibodies and activating immune cells.

Conventional vaccines introduce weakened, dead, or noninfectious parts of a virus or bacterium to the body. By contrast, mRNA vaccines give the body instructions for making its own viral or bacterial proteins. The immune system then responds by creating antibodies.

Benefits of mRNA vaccines to traditional vaccines

  • There is no risk of infection by the vaccine because mRNA vaccines do not introduce a live virus to the body.
  • Unlike conventional vaccines, mRNA vaccines are not grown in live cells. This can speed up the manufacturing process. mRNA vaccines also bypass the step of inactivating viruses or isolating the protein, which also makes them quicker to produce.
  • mRNA vaccines are more effective against germs that evolve through mutation. That’s because RNA vaccines typically trigger an immune response to a part of the virus (the viral stalk) that doesn’t mutate easily. Traditional vaccines typically target a different part of the virus (the globular head), which does mutate easily.

Who Can Get an mRNA COVID-19 Vaccine?

The FDA has authorized the Pfizer and Moderna vaccines in Americans 6 months and up. The initial vaccination series calls for two doses over a multi-week span, with different dosages depending on your age. Many Americans are eligible for additional or booster doses in the months after they receive their initial vaccination doses.

For more information on COVID-19 vaccination, visit our website.

Editor's Note: This article was originally published on , and was last reviewed on .

The Science and Fundamentals of mRNA Technology. Moderna. Link

Why so many people are hopeful about an mRNA coronavirus vaccine. CNBC. Link

Moderna's mRNA vaccine reaches its final phase. Here's how it works. National Geographic. Link

Vaccine Chaos Is Looming. The Atlantic. Link

Pfizer and BioNTech Announce Vaccine Candidate Against COVID-19 Achieved Success in First Interim Analysis from Phase 3 Study. Pfizer. Link

How Scientists Could Stop the Next Pandemic Before It Starts. The New York Times. Link

Candidate for universal flu vaccine protects against multiple strains. Science Daily. Link

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