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Pfizer-BioNTech COVID-19 Vaccine Overview and Safety

Pfizer-BioNTech COVID-19 Vaccine Overview and Safety

NOTICE: FDA authorizedexternal iconexternal icon the Pfizer-BioNTech COVID-19 Vaccine for emergency use in adolescents 12 and older. The Advisory Committee on Immunization Practices is meeting on May 12, 2021 to discuss a recommendation for the use of this vaccine for the prevention of COVID-19 in persons aged 12 years and older.

General Information

Name: BNT162b2

Manufacturer: Pfizer, Inc., and BioNTech

Type of Vaccine: mRNA

Number of Shots: 2 shots, 21 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

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 (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:

  • Pain
  • Redness
  • Swelling

Throughout the rest of your body:

  • Tiredness
  • Headache
  • Muscle pain
  • Chills
  • Fever
  • Nausea

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.

Other Authorized and Recommended COVID-19 Vaccines in the U.S.

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—defined as side effects affecting a person’s ability to do daily activities.
  • Although few people in the clinical trials went to the hospital or died, data suggest that people who got the Pfizer-BioNTech vaccine were less likely to have these more serious outcomes compared to people who got the saline placebo.
  • CDC will continue to provide updates as we learn more about the safety of the Pfizer-BioNTech 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 Pfizer-BioNTech vaccine was 95% effective at preventing laboratory-confirmed COVID-19 illness in people without evidence of previous infection.
  • CDC will continue to provide updates as we learn more about how well the Pfizer-BioNTech vaccine works in real-world conditions.

Clinical Trial Demographic Information

Clinical trials for the Pfizer-BioNTech vaccine included people from the following racial and ethnic, age, and sex categories:

  • 81.9% White
  • 9.8% African American
  • 4.4% Asian
  • <3% other races/ethnicities
  • <1% Native Hawaiian or Other Pacific Islander
  • <1% American Indian or Alaska Native


  • 73.2% Not Hispanic or Latino
  • 26.2% Hispanic or Latino
  • <1% Not Reported

Age and sex breakdown:

  • 50.6% male
  • 49.4% female
  • 21.4% 65 years and older​


  • 57.9% 16 to 55 years
  • 41.8% 55 years and older
  • 21.4% 65 years and older​
  • 4.3% 75 years and older

The most frequent underlying medical conditions were obesity (35.1%), diabetes (8.4%), and pulmonary disease (7.8%).