What Are the Ingredients in the COVID-19 Vaccines?

Today, there are three COVID-19 vaccines available in the U.S. The Pfizer and Moderna vaccines use vaccine technology that hadn’t been widely used before. The Novavax vaccine, on the other hand, is similar to more traditional vaccines.

None of the COVID vaccines contain a live virus, antibiotics, or latex. And they don’t contain preservatives, eggs, or metals, either. So, what exactly are the COVID vaccines made of? Let’s discuss.

What is the COVID vaccine made of?

The COVID vaccines all target the spike protein — a part of the SARS-CoV-2 virus that enables it to attach to, enter, and infect our cells to cause COVID. But each vaccine contains different ingredients that help teach your immune system how to recognize this protein. This can include genetic material, proteins, or inactive viruses, along with other components.

Pfizer COVID vaccine ingredients

The Pfizer COVID vaccine is an mRNA vaccine. Some vaccine formulations must be diluted prior to administration, while others do not. Each Pfizer vaccine dose contains genetic material, lipid bubbles, as well as sugar and acid stabilizers. The specific ingredients may be slightly different between the authorized vaccine and the FDA-approved vaccine (Comirnaty).

The authorized Pfizer COVID vaccine ingredients include:

• mRNA

• ((4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate)

• [(polyethylene glycol)-2000]-N,N-ditetradecylacetamide

• 1,2-distearoyl-sn-glycero-3-phosphocholine

• Cholesterol

• Sucrose

• Tromethamine

• Tromethamine hydrochloride

• Sodium chloride injection (yellow cap, multi-dose vial only)

The Comirnaty ingredients include:

• mRNA

• ((4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate)

• 2-(polyethylene glycol 2000)-N,N-ditetradecylacetamide

• 1,2-distearoyl-sn-glycero-3-phosphocholine

• Cholesterol

• Sucrose

• Tromethamine

• Tromethamine hydrochloride

Genetic material

The Pfizer vaccine contains copies of highly-purified messenger RNA (mRNA). This mRNA holds the genetic code for the SARS-CoV-2 spike protein. And it’s produced in laboratory equipment, not in live cells.

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The mRNA in the updated 2024-2025 Pfizer COVID vaccine targets a SARS-CoV-2 strain called KP.2. The amount of mRNA you receive in a dose depends on your age.

Once inside your body, the mRNA instructs your cells to make the spike protein. This triggers an immune response, which results in antibodies being created. These antibodies will be able to identify and help your immune system fight SARS-CoV-2 more quickly if you’re exposed to it in the future.

Lipid (oil) bubbles

Tiny bubbles of lipid (oil) surround and protect the mRNA. This ingredient is essential for the vaccine to work. Without it, your body would destroy the mRNA. And the mRNA wouldn’t be able to enter your cells and provide any benefit. The lipids found inside the Pfizer COVID vaccines include:

• ((4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate)

• [(polyethylene glycol)-2000]-N,N-ditetradecylacetamide or 2-(polyethylene glycol 2000)-N,N-ditetradecylacetamide

• 1,2-distearoyl-sn-glycero-3-phosphocholine

• Cholesterol

Sugar and acid stabilizers

All versions of the Pfizer COVID vaccine contain sugar (sucrose). This ingredient helps keep the molecules in the vaccine stable, especially at different temperatures.

When the Pfizer vaccine was first authorized, it also contained salts to help maintain the vaccine’s acidity and stability. However, the vaccine formulation was changed in December 2021. The new formulation has different acid stabilizers called tromethamine (“tris”) and tromethamine hydrochloride. This change improved the vaccine’s stability and storage time when stored in the refrigerator.

Moderna COVID vaccine ingredients

The Moderna COVID-19 vaccine is also an mRNA vaccine. It’s already in a liquid form and doesn’t need to be diluted before use. The specific ingredients are the same for the authorized vaccine and FDA-approved vaccine (Spikevax), but the amounts of each ingredient can vary.

The Moderna COVID vaccine ingredients include:

• mRNA

• SM-102

• Polyethylene glycol [PEG] 2000 dimyristoyl glycerol [DMG]

• Cholesterol

• 1,2-distearoyl-sn-glycero-3-phosphocholine [DSPC]

• Tromethamine

• Tromethamine hydrochloride

• Acetic acid

• Sodium acetate trihydrate

• Sucrose

Genetic material

Like the Pfizer vaccine, the Moderna vaccine contains mRNA. The updated 2024-2025 Moderna COVID vaccine also targets the KP.2 strain. However, the Moderna vaccine contains more mRNA than the Pfizer vaccine. And the amount you receive in a dose depends on your age.

Lipid (oil) bubbles

The mRNA molecules in the Moderna vaccine are also wrapped in an oily coating. The lipid combination is slightly different from what’s found in the Pfizer vaccine, but it has the same purpose. Without it, the mRNA would be destroyed, and it wouldn’t be able to enter your cells. The lipids found in the Moderna COVID vaccine are:

• SM-102

• Polyethylene glycol [PEG] 2000 dimyristoyl glycerol [DMG]

• Cholesterol

• 1,2-distearoyl-sn-glycero-3-phosphocholine [DSPC]

Sugar, salt, acid, and acid stabilizers

The Moderna vaccine also contains sucrose and the acid stabilizers tromethamine and tromethamine hydrochloride. Additionally, salt (sodium acetate) and acid (acetic acid) are included. These ingredients also help with stability throughout the distribution and storage process.

Novavax COVID vaccine ingredients

The Novavax COVID vaccine is a protein subunit vaccine, which is similar to more traditional vaccines. Another example of a protein subunit vaccine is the hepatitis B vaccine. 

The Novavax vaccine doesn’t need to be diluted. Each Novavax vaccine dose contains viral proteins, adjuvant, lipids, as well as sugar, salt, and acid stabilizers.

The Novavax COVID vaccine ingredients include:

• Spike protein

• Matrix-M adjuvant

• Cholesterol

• Phosphatidylcholine

• Potassium dihydrogen phosphate

• Potassium chloride

• Disodium hydrogen phosphate dihydrate

• Disodium hydrogen phosphate heptahydrate

• Sodium dihydrogen phosphate monohydrate

• Sodium chloride

• Polysorbate 80

• Sodium hydroxide or hydrochloric acid (for pH adjustment)

The vaccine may also contain very small amounts of the following substances from the manufacturing process:

• Baculovirus and Sf9 cell proteins

• Baculovirus and cellular DNA

• Lentil lectin

• Methyl-α-D-mannopyranoside

• Simethicone

• Pluronic F-68

• Triton X-100 

• Tergitol (NP9)

Viral proteins

The Novavax vaccine contains nanoparticles that are made of spike proteins. The spike proteins for the vaccine are grown in moth cells. They’re then extracted, purified, and placed around molecules of a compound called polysorbate 80 to form the nanoparticles. The updated 2024-2025 Novavax COVID vaccine targets the JN.1 viral strain.

Adjuvant

Adjuvants are substances that may be added to help boost your immune response to a vaccine. The Novavax vaccine contains an adjuvant called Matrix-M. It’s made using compounds called saponins from soapbark trees.

Lipids

Lipids are also an important ingredient in creating the Matrix-M adjuvant. They’re combined with the saponins and mixed together to make Matrix-M.

Sugar, salt, and acid stabilizers

Similar to the mRNA vaccines, the Novavax vaccine also contains sugar, salt, and acid stabilizers to help maintain acidity and stability. 

Are any of the COVID vaccine ingredients toxic or dangerous?

No. At the small amounts you receive from a vaccine dose, none of the chemicals above are expected to be toxic or dangerous. They’re also commonly used in other vaccines, medications, and even food products.

But what about mRNA? You have mRNA inside most of your cells already — it’s responsible for carrying instructions to make proteins. And similar to the mRNA made by your body, the vaccine mRNA delivers its instructions and your body gets rid of it shortly after. The mRNA from the vaccine does not affect your DNA, either.

However, certain ingredients in the vaccine may be dangerous if you’re allergic to them. For example, the Pfizer and Moderna vaccines contain polyethylene glycol. And the Novavax vaccine contains polysorbate 80. Some people are allergic to these ingredients.

If you’ve had a severe reaction to any of the ingredients in a vaccine, it’s generally recommended to avoid that vaccine. A healthcare professional can determine which vaccines may or may not be safe for you.

Are there metals in COVID vaccines?

No, the COVID vaccines do not contain any metals, such as iron or nickel. They also do not contain microchips, tracking devices, or the mercury-based preservative thimerosal.

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Written by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Reviewed by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

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