Manufacturer: ModernaTX, Inc.
Type of vaccine: mRNA
Learn more about how COVID-19 vaccines work and get a better understanding of COVID-19 mRNA vaccines.
Number of shots: 2 shots, one month (28 days) apart
How given: Shot in the muscle of the upper arm
Does not contain:
For a full list of ingredients, see Moderna’s COVID-19 Vaccine Fact Sheet for Recipients and Caregivers
Who should get vaccinated
Who should not get vaccinated
- If you have had a severe allergic reaction (anaphylaxis) or an immediate allergic reaction—even if it was not severe—to any ingredient in an mRNA COVID-19 vaccine, you should not get an mRNA COVID-19 vaccine.*
- If you have had a severe allergic reaction (anaphylaxis) or an immediate allergic reaction—even if it was not severe—after getting the first dose of the vaccine, you should not get another dose of an mRNA COVID-19 vaccine.*
- An immediate allergic reaction means a reaction within 4 hours of getting vaccinated, including symptoms such as hives, swelling, or wheezing (respiratory distress).
- This includes allergic reactions to polyethylene glycol (PEG) and polysorbate. Polysorbate is not an ingredient in either mRNA COVID-19 vaccine but is closely related to PEG, which is in the vaccines. People who are allergic to PEG or polysorbate should not get an mRNA COVID-19 vaccine.
Learn more about COVID-19 vaccines and allergic reactions.
*If you have had an immediate allergic reaction—even if the reaction was not severe—to a vaccine or injectable therapy for another disease, ask your doctor if you should get a COVID-19 vaccine. Your doctor will help you decide if it is safe for you to get vaccinated.
Side effects and safety information
Most common side effects
In the arm where you got the shot:
Throughout the rest of your body:
These side effects usually start within a day or two of getting the vaccine. They might feel like flu symptoms and might even affect your ability to do daily activities, but they should go away in a few days. Get tips on what to expect after getting vaccinated.
Summary of safety data
- In clinical trials, reactogenicity symptoms (side effects that happen within 7 days of getting vaccinated) were common but were mostly mild to moderate.
- Side effects (such as fever, chills, tiredness, and headache) throughout the body were more common after the second dose of the vaccine.
- Most side effects were mild to moderate. However, a small number of people had severe side effects that affected their ability to do daily activities.
- CDC will continue to provide updates as we learn more about the safety of the Moderna vaccine in real-world conditions. Learn more about vaccine safety monitoring after a vaccine is authorized or approved for use.
Learn more about safety and reactogenicity data from the clinical trials.
Information on how well the vaccine works
- Based on evidence from clinical trials, the Moderna vaccine was 94.1% effective at preventing laboratory-confirmed COVID-19 illness in people who received two doses who had no evidence of being previously infected.
- The vaccine appeared to have high effectiveness in clinical trials (efficacy) among people of diverse age, sex, race, and ethnicity categories and among persons with underlying medical conditions.
- Although few people in the clinical trials were admitted to the hospital, this happened less often in the people who got the Moderna vaccine compared to people who got the saline placebo.
- CDC will continue to provide updates as we learn more about how well the Moderna vaccine works in real-world conditions.
Demographic information from clinical trials
Clinical trials for the Moderna vaccine included people from the following racial and ethnic categories:
- 79.4% White
- 20% Hispanic/Latino
- 9.7% African American
- 4.7% Asian
- <3% other races/ethnicities
Age and sex breakdown:
- 52.6% male
- 47.4% female
- 25.3% 65 years and older
Most people who participated in the trials (82%) were considered to have an occupational risk of exposure, with 25.4% of them being healthcare workers.
Among people who participated in the clinical trials, 22.3% had at least one high-risk condition, which included lung disease, heart disease, obesity, diabetes, liver disease, or HIV infection. Four percent (4%) of participants had two or more high-risk conditions.
Information sources from the Center for Disease Control & Prevention.