How do different types of COVID-19 vaccines work? (2025)

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Different types of COVID-19 vaccines: How they work Messenger RNA (mRNA) vaccine mRNA vaccine mRNA vaccine Vector vaccine Viral vector vaccine Viral vector vaccine Protein subunit vaccine Protein subunit vaccine Protein subunit vaccine COVID-19 vaccines Related chart From Mayo Clinic to your inbox Products and Services See also References

Different types of COVID-19 vaccines: How they work

Understand how different vaccine technologies work with the immune system to provide protection.

By Mayo Clinic Staff

COVID-19 vaccines lower your risk of getting sick, seriously ill or dying from the disease. But how do the different types of COVID-19 vaccines work?

Each COVID-19 vaccine causes the immune system to create proteins called antibodies. These proteins fight infection with the COVID-19 virus. COVID-19 vaccines use a harmless version of a spikelike structure called an S protein on the surface of the COVID-19 virus.

There are a few main types of COVID-19 vaccines.

Messenger RNA (mRNA) vaccine

mRNA vaccine

An mRNA vaccine gives cells instructions for how to make the S protein found on the surface of the COVID-19 virus. After vaccination, the body's muscle cells begin making the protein pieces and showing them on cell surfaces. This causes the body to create antibodies. Then if you catch the COVID-19 virus, these antibodies are used to help clear out the virus.

Vector vaccine

Viral vector vaccine

In this type of vaccine, material from the virus that causes COVID-19 is placed in a modified version of a different virus. This different virus is called a viral vector. The viral vector gives cells instructions to make copies of the COVID-19 virus S protein.

Once the cells display the S proteins on their surfaces, the immune system responds by creating antibodies and defensive white blood cells. If infection with the virus that causes COVID-19 happens later, the antibodies help clear out the virus.

Viral vector vaccines can't cause infection with the COVID-19 virus or the viral vector virus. The Johnson & Johnson COVID-19 vaccine is a vector vaccine that's no longer used in the United States.

Protein subunit vaccine

Subunit vaccines include only the parts of a virus that best stimulate the immune system. This type of COVID-19 vaccine has harmless S proteins in it. Once the immune system recognizes the S proteins, it creates antibodies and defensive white blood cells. If infection with the COVID-19 virus happens later, the antibodies help clear out the virus.

The Novavax COVID-19 vaccine is a protein subunit vaccine.

COVID-19 vaccines

The COVID-19 vaccines available in the United States are:

Pfizer-BioNTech COVID-19 vaccine 2024-2025 formula, available for people age 6 months and older.
Moderna COVID-19 vaccine 2024-2025 formula, available for people age 6 months and older.
Novavax COVID-19 vaccine, adjuvanted 2024-2025 formula, available for people age 12 years and older.

Getting vaccinations as they are updated and on schedule gives you the best protection against COVID-19.

Related chart

Comparing the differences between COVID-19 vaccines - Related chartComparing the differences between COVID-19 vaccines

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Jan. 30, 2025

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