Developed by Massachusetts-based biotechnology company Moderna Therapeutics, this COVID-19 vaccine was authorized for emergency use by the U.S. Food and Drug Administration on December 18, 2020.

Important Information about the Moderna Vaccine

  • Number of doses required: 2 doses of the same vaccine
  • Time between dose: Minimum of 28 days
  • Third dose for immunocompromised people: Yes
  • FDA status: Ages 18 and up (FDA EUA)
  • Time to reach full protection: 14 days after second dose
  • Effectiveness: Highly effective in preventing severe illness, hospitalization and death
  • How long protection will last: Unknown at this time; studies are ongoing
  • Storage: Freezer (-13 to 5 degrees Fahrenheit)

How the Moderna Vaccine Works

Both the Moderna and Pfizer (Comirnaty) vaccines are based on messenger RNA (mRNA) technology. mRNA vaccines contain a code that provides the cells "instructions" to create antibodies to protect against COVID-19. Learn more about how mRNA vaccines work.

This type of vaccine does not contain any part of the virus, so it cannot cause COVID-19.

Who Can and Cannot Get the Moderna Vaccine

The vast majority of people are able to get the Moderna vaccine or any of the other approved vaccines. However, a few groups of people cannot receive the vaccine or should talk to a doctor first.

  • Children under the age of 18 are not eligible to receive the Moderna 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 Moderna vaccine. The CDC has recommended that women who are pregnant, breastfeeding or plan to become pregnant be vaccinated against COVID-19. Please see the recommendations from the CDC about COVID-19 Vaccines While Pregnant or Breastfeeding.
  • People who are allergic to any of the vaccine's ingredients or those who had an allergic reaction to their first dose cannot receive this vaccine. Please see additional information about allergic reactions below.

Third Dose for Immunocompromised People

In August 2021, both the FDA and the CDC approved a third dose of mRNA vaccines (Pfizer and Moderna) for moderately to severely immunocompromised people age 18 and up, to be given 28 days or more after their second dose of the vaccine.

For more information, please see the CDC’s recommendations for immunocompromised people.

How the Moderna Vaccine Was Developed

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

In September 2020, University of Maryland School of Medicine became one of the clinical research sites working on phase three testing of this vaccine. A key focus of this trial was to include people most impacted by COVID-19, including those from the African American and Latino communities. Learn more about how we're fighting COVID at the University of Maryland Medical System.

Allergic Reactions and Side Effects

Please see the FDA's Fact Sheet for the Moderna vaccine or 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 (see additional information above)
  • 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
  • Have received another COVID-19 vaccine

Updated 8/30/2021

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