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About the Vaccine


Last updated 10/18/2022

COVID-19 vaccines protect against severe illness, hospitalization and death. A safe, effective, free COVID-19 vaccine is available to everyone ages 6 months and older. Everyone should stay up-to-date on vaccinations by getting booster shots when eligible.

Why Should I Get Vaccinated?

The vaccines give you strong protection from serious illness, hospitalization and death from the virus. Together, the vaccine and other healthy habits, like wearing a high-quality mask (KN95 or N-95) and improving air flow in indoor spaces, offer the best protection from COVID-19.

There’s no way to know how COVID-19 will affect you. Some people may suffer from long COVID (also known as post-COVID conditions) which includes a wide range of ongoing or new health problems and symptoms that can be difficult to explain, manage or treat. The best way to avoid long COVID is to avoid infection, including getting vaccinated and staying up to date with boosters. Learn more about long COVID.


Am I Up-to-Date on My Vaccination?

A person is up-to-date with their COVID-19 vaccination if they have received all recommended doses in the primary series and boosters for their age group.

  • People ages 6 months through 4 years must complete the initial COVID-19 vaccination primary series and get an Omicron booster, if eligible, to be considered up-to-date.

  • People ages 5+ years must complete the primary vaccination series and get an Omicron booster to be considered up-to-date. 

How Do the Vaccines Work?

There are four COVID-19 vaccines approved in the United States and each one teaches our bodies how to fight the virus and helps prevent severe illness, hospitalization and death. Though different vaccines use different methods to provide protection, all vaccines help our bodies protect us from getting very sick from COVID-19.

Pfizer and Moderna

The Pfizer and Moderna vaccines use messenger RNA (mRNA) to teach the body's cells to produce antibodies to fight COVID-19. After the body produces antibodies, it gets rid of all of the vaccine ingredients, just as it would get rid of any substance that cells no longer need. Both of these vaccines require two doses for the initial series. Because protection from the mRNA vaccines lessens over time, it is recommended that people stay up-to-date on their vaccinations by getting booster shots when eligible. Learn more about booster doses.



Novavax is a protein subunit vaccine, which uses harmless pieces (proteins) of the virus that causes COVID-19. Protein-based vaccines have been used widely for decades and include vaccines to prevent hepatitis B and shingles. Novavax was authorized by the FDA and CDC in July 2022 as a two-dose primary series, given at least three weeks apart, in people ages 18 years and older. Novavax has not been approved for use as a booster.


Johnson & Johnson/Janssen

The Johnson & Johnson/Janssen vaccine is a viral vector vaccine, which uses a modified version of a different (and harmless) virus to give important instructions to our cells so they can fight infections. Based on an updated risk-benefit analysis, it is preferred that people get an mRNA COVID-19 vaccine (Pfizer or Moderna) instead of the Johnson & Johnson vaccine. People who originally received Johnson & Johnson for their first shots should get a booster shot of Pfizer or Moderna.


For more information, see the CDC’s U.S. COVID-19 Vaccine Product Information page and the Interim COVID-19 Immunization Schedule for 6 Months of Age and Older.

Are the Vaccines Safe?

Yes. Although the vaccines were developed in record time, they have gone through the same rigorous Food and Drug Administration (FDA) process as every other vaccine, meeting all safety standards. No steps were skipped. In fact, the state of California added another step by creating its own safety-review committee. Millions of people have been safely vaccinated around the world already.


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