Moderna COVID-19 Vaccine Overview and Safety
Manufacturer: ModernaTX, Inc.
Type of Vaccine: mRNA
Number of Shots: 2 shots, one month (28 days) apart
How Given: Shot in the muscle of the upper arm
Does NOT Contain: Eggs, preservatives, latex
Full List of Ingredients [PDF – 6 pages]external icon
- The Moderna vaccine is recommended for people aged 18 years and older. Learn more about how CDC is making COVID-19 vaccine recommendations and CDC’s vaccine rollout recommendations.
- 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 (such as polyethylene glycol), you should not get an mRNA COVID-19 vaccine.*
- or after getting the first dose of the vaccine, you should not get a second dose of either of the mRNA COVID-19 vaccines.
- An allergic reaction is considered severe when a person needs to be treated with epinephrine or EpiPen©or if they must go to the hospital. Learn about common side effects of COVID-19 vaccines and when to call a doctor.
- An immediate allergic reaction means a reaction within 4 hours of getting vaccinated, including symptoms such as hives, swelling, or wheezing (respiratory distress).
If you aren’t able to get an mRNA COVID-19 vaccine, you may still be able to get a different type of COVID-19 vaccine. Learn more information for people with allergies.
Possible Side Effects
In the arm where you got the shot:
Throughout the rest of your body:
- Muscle pain
These side effects usually start within a day or two of getting the vaccine. Side effects might affect your ability to do daily activities, but they should go away in a few days.
You should get the first COVID-19 vaccine that is available to you. Do not wait for a specific brand. All currently authorized and recommended COVID-19 vaccines are safe and effective, and CDC does not recommend one vaccine over another.
Safety Data Summary
- 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.
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.
Clinical Trial Demographic Information
Clinical trials for the Moderna vaccine included people from the following racial and ethnic, age, and sex categories:
- 79.4% White
- 9.7% African American
- 4.7% Asian
- <3% other races/ethnicities
- <1% American Indian or Alaska Native
- <1% Native Hawaiian or Other Pacific Islander
- 79.1% Not Hispanic or Latino
- 20.0% Hispanic or Latino
- 0.9% Unknown
- 52.6% male
- 47.4% female
- 74.7% 18 – 64 years
- 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.