mRNA Vaccine

What is an mRNA vaccine?

An mRNA vaccine is a preventive treatment that helps your body learn to fight diseases. A healthcare provider gives you the vaccine in a shot or series of shots. 

The only mRNA vaccines currently available are to protect against COVID-19. They include:

• Comirnaty^® (Pfizer-BioNTech vaccine).
• Spikevax^® (Moderna vaccine).

Scientists are investigating other ways to use mRNA technology in vaccines for other infectious diseases and cancer.

What is mRNA?

MRNA — or messenger ribonucleic acid — is a molecule in your cells that copies instructions from your DNA and brings them to your ribosomes (protein-making structures in your cells). Your ribosomes use the instructions on mRNA to create proteins that make your body work.

The mRNA in vaccines carries the instructions for making a single part of a pathogen (germ) so that your immune system can recognize it. 

How do mRNA vaccines work?

Like all vaccines, mRNA vaccines work by training your body to recognize and create tools to fight something harmful (like a virus). For COVID mRNA vaccines, they do this by giving your cells the mRNA instructions they need to make the spike protein — a unique, recognizable part of SARS-CoV-2 (the virus that causes COVID-19).

Ideally, your body responds to the protein by recognizing it as an invader. Your immune system creates tools — like antibodies — to fight an infection off more quickly the next time it sees the same protein.

Just like the mRNA your body produces for its own instructions, the mRNA from the vaccines breaks down in your body in a few days.

What is the difference between traditional vaccines and mRNA vaccines?

The difference between mRNA vaccines and traditional vaccines is how they get your immune system to recognize a virus. Other vaccines use a deactivated (“killed”) virus, a weakened virus, or parts of the virus (protein subunit). MRNA vaccines don’t use any parts of a virus, but instead give your body instructions to make a recognizable part of the virus.

Are all COVID vaccines mRNA?

No. The Novavax® vaccine isn’t an mRNA vaccine; it’s a protein subunit vaccine. It uses a piece of the SARS-CoV-2 virus to activate the immune response in your body.

What happens when you get an mRNA vaccine?

Healthcare providers give mRNA vaccines as injections (shots). A provider will:

1. Clean your upper arm (or leg, in young children) with an alcohol swab.
2. Inject the vaccine with a needle. Sometimes, they’ll put a small, round bandage (a pre-injection bandage, or an Inject-Safe™ barrier bandage) on first and inject the needle into your skin through the bandage.
3. Put a bandage over the injection site (if not using the pre-injection bandage).

Your provider may ask you to wait at least 15 minutes before leaving to make sure you don’t have an immediate allergic reaction. You may want to sit while you wait if shots make you feel faint.

What are the advantages of mRNA vaccines?

Compared to other types of vaccines, mRNA technology allows researchers to develop vaccines quickly, since labs don’t have to grow copies of the virus. This can mean creating enough vaccines for everyone (once developed) in just weeks, instead of months.

Compared to not getting vaccinated, mRNA vaccines (and any current COVID vaccine) can reduce your risk of:

• Getting infected with COVID-19.
• Getting seriously ill or being hospitalized due to COVID-19.
• Developing long COVID after a COVID-19 infection. 

What are the risks of mRNA vaccines?

Risks of mRNA vaccines include side effects and allergic reactions.

Side effects of mRNA COVID vaccines include:

• Pain or swelling where you got the injection.
• Fatigue.
• Headache.
• Muscle aches.
• Fever.

You could have an allergic reaction to one of the ingredients in the vaccine. Signs of an allergic reaction include:

• Skin rash.
• Itching.
• Hives.
• Swelling of your face, lips, tongue or throat (anaphylaxis).

When should I call my healthcare provider?

Go to an emergency room immediately if you have signs of a severe allergic reaction, including trouble breathing, severe hives or swelling of your face, lips, tongue or throat.

Talk to your healthcare provider if you have concerns about mRNA vaccines or which COVID vaccine is right for you.

What’s the history of mRNA vaccines?

Research into mRNA technology dates back to the 1970s. Scientists first started applying it to vaccine development in the 1990s. It took over 20 years of research to learn how to get our immune systems to recognize the mRNA without destroying it too quickly, and how to get it into our cells.

Finally, in 2018, the FDA approved patisiran (Onpattro^®), a drug that treats a rare nerve disease. The method patisiran uses to deliver RNA (lipid nanoparticles) paved the way for Moderna and Pfizer-BioNTech to use it in their COVID vaccines. The FDA authorized the first COVID vaccines for emergency use in the U.S. in December of 2020.