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COVID-19 Vaccines

Information and evidence about COVID-19 vaccine efficacy and safety

MODERNA COVID-19 VACCINE

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.

SOURCE: CDC - https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/Moderna.html (April 15, 2021)

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.

SOURCE: CDC - https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/Moderna.html (April 15, 2021)

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

Ethnicity:

  • 79.1% Not Hispanic or Latino
  • 20.0% Hispanic or Latino
  • 0.9% Unknown

Sex breakdown:

  • 52.6% male
  • 47.4% female

Age breakdown:

  • 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.

 

SOURCE: CDC - https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/Moderna.html (April 15, 2021)