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Developed by Janssen Pharmaceuticals, a division of New Jersey-based Johnson & Johnson (J&J), this COVID-19 vaccine was authorized for emergency use by the U.S. Food and Drug Administration (FDA) on February 27, 2021.

Important Information about the Johnson & Johnson (Janssen) Vaccine

  • Number of doses required: 1 dose
  • Authorized for: People age 18 and up
  • Time to reach full protection: 28 days after vaccination
  • Effectiveness: Nearly 100% effective in preventing hospitalization and death
  • How long protection will last: Unknown at this time; studies are ongoing
  • Storage: Refrigeration

How the Johnson & Johnson Vaccine Works

The Johnson & Johnson vaccine is a viral vector vaccine that uses a modified version of an inactive virus (not the virus that causes COVID-19, but a different, harmless virus) to make what is called "spike protein." This triggers an immune response in our bodies, causing our immune system to produce antibodies to fight future infection from the virus that causes COVID-19. Viral vector vaccines do not affect or interact with your DNA in any way. Similar to the Pfizer and Moderna vaccines, you cannot get COVID-19 from this vaccine.

Who Can and Cannot Get the Johnson & Johnson Vaccine

The vast majority of people will be able to get the Johnson & Johnson vaccine or any of the other approved vaccines when it's their turn and they are eligible. However, a few groups of people cannot receive it or should consult a doctor first.

  • Children under the age of 18 are not eligible to receive the Johnson & Johnson vaccine at this time. Studies are under way to test its safety and effectiveness in children.
  • Pregnant women, as well as those who are breastfeeding or may become pregnant, may receive the Johnson & Johnson vaccine. However, they should talk to their doctor first because clinical testing in this group has not been completed.
  • People who are allergic to any of its ingredients should not receive this vaccine. Please see additional information about allergic reactions below.

How the Johnson & Johnson Vaccine Was Developed

Although the vaccine was developed quickly, it underwent the same rigorous approval process as laid out by the FDA. No safety steps were skipped. Learn more about the vaccine's development and approval process.

The Johnson & Johnson COVID-19 vaccine trials evaluated the safety and effectiveness of the vaccine in protecting against both moderate and severe COVID-19 disease. The trial included a diverse population of participants across eight countries on three continents.

Allergic Reactions and Side Effects

Please see the FDA's Fact Sheet for the Johnson & Johnson vaccine for the most up-to-date information on:

  • Vaccine ingredients
  • Side effects and what to do about them
  • Possible allergic reactions

If you have a history of immediate or severe allergic reaction to anything – especially another vaccine or injectable medicine – it is strongly recommended you talk to your doctor before getting the vaccine. This is so your doctor can confirm it is safe for you to get the vaccine.

If you have a history of severe allergic reactions, you will also be monitored for 30 minutes after your vaccination.

Other Conditions

Before you get vaccinated, you should talk to your doctor if you:

  • Have any allergies
  • Have a fever
  • Have a bleeding disorder or are on a blood thinner
  • Are immunocompromised or are taking a medicine that affects your immune system
  • Are pregnant or plan to become pregnant
  • Are breastfeeding
  • Have received another COVID-19 vaccine

Updated 7/21/2021

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