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What you need to know about the Pfizer COVID-19 vaccine

  • December 15, 2020
As the first FDA-approved COVID-19 vaccine begins to be administered, many Americans still have questions. UAB has you covered.

Editor's Note: The information published in this story is accurate at the time of publication. Always refer to for UAB's current guidelines and recommendations relating to COVID-19.

vaccine nycu.3As the first FDA-approved COVID-19 vaccine begins to be administered, many Americans still have questions. UAB has you covered. Photography: Steve WoodOn Friday, Dec. 11, the United States Food and Drug Administration officially approved use of the Pfizer/BioNTech COVID-19 vaccine. Here is a primer on what you need to know.

How effective is the vaccine?

According to clinical trial results, the Pfizer/BioNTech COVID-19 vaccine is 95 percent effective at preventing COVID-19, and even with the margin of error, it is at least 90 percent effective.

What is in the vaccine, and how does it work?

The active ingredient in the vaccine is messenger RNA that carries instructions for making the virus’s spike protein. The spike protein is recognized by the body’s immune system to develop protection from infection. The mRNA is synthetic, not extracted from actual viruses, and it does not enter or interact with the body’s own DNA.

When germs, such as viruses, invade the body, they attack and multiply. This invasion, called an infection, is what causes illness. The immune system uses several tools to fight infection. The first time the body encounters a germ or virus, it can take several days for the body to make and use all the germ-fighting tools needed to fight the infection. After the infection, the immune system remembers what it learned about how to protect the body against that disease. Vaccines help develop immunity by imitating an infection. Vaccines greatly reduce the risk of infection by working with the body’s natural defenses to safely develop immunity to disease. 

While some vaccines, such as flu vaccines, use dead or deactivated virus to imitate the infection, the vaccine approved for COVID-19 does not. It uses the body’s messenger RNA to teach the immune system to recognize the SARS-CoV-2 virus. A person cannot get COVID-19 from the vaccine.

How many doses will be needed?

The Pfizer/BioNTech COVID-19 vaccine requires two separate shots separated by 21 days.

Is the vaccine safe?

According to the U.S. FDA, there were no safety concerns identified in the 43,448 participants in the trial and no enhanced disease in the recipients.

The CDC recommends that people who have experienced severe reactions to prior vaccines or injectable drugs can still get the Pfizer/BioNTech vaccine for COVID-19, but should discuss the risks with their doctors and be monitored for 30 minutes afterward.

The American College of Obstetricians and Gynecologists recommends that COVID-19 vaccines should not be withheld from pregnant individuals who meet criteria for vaccination based on ACIP-recommended priority groups.

How long does it take to build immunity after getting the vaccine?

It typically takes a few weeks for the body to build immunity after vaccination. That means it is possible a person could be infected with the virus that causes COVID-19 just before or just after vaccination and get sick. This is because the vaccine has not had enough time to provide protection.

Entrance/line location for vaccination areaPhotography: Steve WoodAre there any side effects to the vaccine?

The immune response to vaccination can lead to sore arm, fatigue and headache in some, especially after the second dose. Symptoms usually resolve on their own in 24 hours.

Who is able to receive the vaccine first?

In Alabama, the vaccine will be distributed and administered to frontline health care workers and residents of long-term care facilities like nursing homes. UAB will get a percentage of the vaccine allotment for UAB frontline workers, but will also be allocating and administering vaccines for ambulatory, EMS and other hospitals. The vaccine is expected to be distributed to the general public by late spring or summer 2021.

Will I be required to get the vaccine?

The Alabama Department of Public Health will not require persons to receive the vaccine.

Editor’s note: The information in this release was reviewed and fact-checked by UAB Associate Professor of Infectious Diseases Jodie Dionne-Odom.

As of December 15, we are not currently offering Covid vaccines to patients. This is because there is a limited supply of COVID-19 vaccine available, and the CDC and the Alabama Department of Public Health (ADPH) has issued guidance that the first vaccines should go to health care teams, emergency service workers, and long-term care facilities. We are carefully monitoring this situation as it evolves and will make sure that our UAB Medicine patients are notified and are given the opportunity to receive a vaccine once the vaccine is made available to the public, consistent with CDC and ADPH guidance. Please note that it could be early spring before the vaccine is more widely available to the public. We do not have additional information on when the vaccine will be available to you but will continue to communicate as we learn new information.