A coronavirus disease 2019 (COVID-19) vaccine can help you develop immunity to SARS-CoV-2, the virus that causes COVID-19, without getting ill. While each type of vaccine works in a different way, all COVID-19 vaccines prompt an immune response so that your body remembers how to fight the virus in the future.

The safety of the COVID-19 vaccines is being closely monitored by the U.S. Centers for Disease Control and Prevention and the U.S. Food and Drug Administration (FDA). Even after a vaccine is authorized for use, vaccine safety monitoring systems continue to watch for side effects.

Here's what you need to know about the different COVID-19 vaccines:

What vaccines are available?

Illustration of virus and antibodies

Pfizer-BioNTech vaccine

  • mRNA vaccine
  • 95% effective at preventing the COVID-19 virus with symptoms
  • FDA emergency use authorization
  • Greater than 89% effective in preventing people with health conditions, such as diabetes or obesity, from developing the COVID-19 virus with symptoms
  • Doesn't contain eggs, latex or preservatives

Moderna vaccine

  • mRNA vaccine
  • 94% effective at preventing the COVID-19 virus with symptoms
  • FDA emergency use authorization
  • Greater than 90% effective in preventing people with health conditions, such as diabetes or obesity, from developing the COVID-19 virus with symptoms
  • Doesn't contain eggs, latex or preservatives

Janssen/Johnson & Johnson

  • Vector vaccine
  • 66% effective at preventing the COVID-19 virus with symptoms
  • 85% effective at preventing the COVID-19 virus with severe illness
  • FDA emergency use authorization
  • Doesn't contain eggs, latex or preservatives

How many doses are needed, and when does protection start?

Illustration of clock and calendar

Pfizer-BioNTech vaccine

  • Two doses are needed, 21 days apart (or up to six weeks apart, if needed)
  • Some protection provided after the first dose

Moderna vaccine

  • Two doses are needed, 28 days apart (or up to six weeks apart, if needed)
  • Some protection provided after the first dose

Janssen/Johnson & Johnson

  • One dose is needed
  • Some protection provided two weeks after vaccination

Who should or shouldn't get the vaccine?

Illustration of masked people

Pfizer-BioNTech vaccine

People age 16 and older should get the vaccine

Moderna vaccine

People age 18 and older should get the vaccine

Pfizer-BioNTech and Moderna:

  • People who've had an immediate or severe allergic reaction to any of the vaccine's ingredients or after a prior dose of the vaccine and people who are allergic to polysorbate shouldn't get the vaccine
  • People who've had an immediate allergic reaction to any vaccine or injectable medication should be cautious about getting the vaccine

Janssen/Johnson & Johnson

  • People age 18 and older should get the vaccine
  • People who've had a severe allergic reaction to any of the vaccine's ingredients shouldn't get the vaccine

What are the vaccine's possible side effects?

Illustration of masked people

Pfizer-BioNTech vaccine

Injection site pain, fatigue, headache, muscle pain, chills, joint pain, fever, nausea, feeling unwell and swollen lymph nodes

Moderna vaccine

Injection site pain, fatigue, headache, muscle pain, chills, joint pain, swollen lymph nodes in the arm that was injected, nausea, vomiting and fever

Janssen/Johnson & Johnson

Injection site pain, headache, fatigue, muscle pain and nausea

If you have any questions or concerns about getting a COVID-19 vaccine, talk to your doctor.

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  2. Interim clinical considerations for use of mRNA COVID-19 vaccines currently authorized in the United States. Centers for Disease Control and Prevention. https://www.cdc.gov/vaccines/covid-19/info-by-product/clinical-considerations.html?CDC_AA_refVal=https://www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/clinical-considerations.html. Accessed March 1, 2021.
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  9. About COVID-19 vaccine. Minnesota Department of Health. https://www.health.state.mn.us/diseases/coronavirus/vaccine/basics.html. Accessed Jan. 13, 2021.
  10. Moderna COVID-19 vaccine: Fact sheet for recipients and caregivers. U.S. Food and Drug Administration. https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/moderna-covid-19-vaccine#additional. Accessed Jan. 27, 2021.
  11. Pfizer-BioNTech vaccine: Fact sheet for recipients and caregivers. U.S. Food and Drug Administration. https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/pfizer-biontech-covid-19-vaccine. Accessed Jan. 27, 2021.
  12. Frequently asked questions about COVID-19 vaccination. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/faq.html. Accessed Jan. 27, 2021.
  13. Ensuring the safety of COVID-19 vaccines in the United States. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety.html. Accessed Jan. 27, 2021.
  14. Janssen COVID-19 vaccine: Fact sheet for recipients and caregivers. U.S. Food and Drug Administration. https://www.fda.gov/emergency-preparedness-and-response/mcm-legal-regulatory-and-policy-framework/emergency-use-authorization#vaccines. Accessed March 1, 2021.
  15. Understanding viral vector COVID-19 vaccines. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/viralvector.html. Accessed March 1, 2021.
  16. Janssen COVID-19 vaccine: Fact sheet for healthcare providers administering vaccine. U.S. Food and Drug Administration. https://www.fda.gov/emergency-preparedness-and-response/mcm-legal-regulatory-and-policy-framework/emergency-use-authorization#vaccines. Accessed March 1, 2021.
  17. Janssen COVID-19 frequently asked questions. U.S. Food and Drug Administration. https://www.fda.gov/emergency-preparedness-and-response/mcm-legal-regulatory-and-policy-framework/janssen-covid-19-vaccine-frequently-asked-questions. Accessed March 1, 2021.