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All vaccines are tested and reviewed by the FDA to make sure they work and are safe. Learn more about the approval process.

UNC Health is committed to making COVID-19 vaccines available to our co-workers and our community as early as possible. We are taking every step to examine the safety of each COVID-19 vaccine, and it is important that everyone has the facts they need to protect themselves.

Some people have questions about the COVID-19 vaccine approval processes and want to make sure the urgency of the crisis hasn’t allowed for any cut corners when it comes to safetyIt’s understandable to wonder if manufacturers have followed the right steps and if the vaccines are safe.

It is true that through Operation Warp Speed, a partnership between government agencies and private organizations to quickly and safely develop vaccines, the process is being accelerated. However, this process has not removed the steps that ensure safety for all vaccines, like those used to prevent the chicken pox or polio. Instead, parts of the process are happening at the same time, such as starting manufacturing during the approval process.[1] Also, vaccines were developed quickly for two other reasons: many vaccine researchers dropped everything to focus on COVID-19 vaccines, and the federal government provided funding for clinical trials. But no safety review hurdles were eliminated.

Who approves vaccines?

In the U.S., the Food and Drug Administration (FDA) ensures the safety and effectiveness of vaccines, and all vaccines must meet the FDA’s high safety and quality standards.[2]

There is no official timeline for developing a vaccine,[3] and in a public health emergency, manufacturers can have vaccines released through an Emergency Use Authorization, which does not affect vaccine safety.[4]

It is true that the approval process was sped up to quickly and safely develop vaccines. However, this process has not removed the steps that ensure safety for all vaccines, like those used to prevent the chicken pox or polio. UNC Health and our providers are confident in the safety and effectiveness of these vaccines.

Vaccines start with research

Vaccines work by tricking our body into thinking a virus or bacteria that causes disease is attacking it. This fires up our immune system and builds up resistance so if we are exposed to the disease, our body knows how to fight it.

Researchers develop what’s called a vaccine candidate, and if the candidate looks promising after initial testing, manufacturers—the companies that make vaccines—submit the researchers’ data to the FDA for approval so they can begin clinical trials.

Beginning in March 2020, several COVID-19 vaccine candidates have been developed and approved for testing, including vaccines from Moderna and Pfizer.[5]

Testing is essential for safety

Clinical trials are conducted in three phases.[6]

  1. In Phase 1, the vaccine is given to a small number of generally healthy people to test its safety and effectiveness.
  2. In Phase 2, the vaccine is given to hundreds of people with different health conditions and from different races and ethnicities.
  3. In Phase 3, thousands of people across diverse demographic groups received the vaccine, and immune responses are compared against placebos, which are doses that do not contain any of the vaccine and are used for testing purposes only.

Moderna and Pfizer began Phase 3 trials in July 2020.[7] More than 43,000 people across all demographic groups participated in the Pfizer vaccine clinical trial,[8] and more than 30,000 people participated in the Moderna clinical trial.[9]

In fact, UNC Health participated in the Moderna clinical trial, and more than 174 volunteers received either the vaccine or placebo. Further, in addition to federal reviews, the COVID-19 vaccine candidates have been evaluated by a team of epidemiology and infectious disease experts across UNC Health and the UNC School of Medicine, including Drs. David Weber, David Wohl, Cynthia Gay, and Crystal Cené.

Results are reviewed closely before approval

Once Phase 3 trials are complete, the FDA reviews the data to determine whether the vaccine works and is safe. If so, the manufacturer files for approval. If the benefits outweigh any possible risks of the vaccine, and manufacturing quality can be ensured, the FDA will approve the vaccine for use.

Early clinical results show that two COVID-19 vaccines are about 95% effective at preventing people from getting sick with the virus, and Moderna and Pfizer filed for Emergency Use Authorizations in November 2020. These vaccines were approved for emergency use in December 2020.

What’s next?

As a nation and a community, the availability of a safe and effective vaccine is an exciting step toward our ability to return to the lives we once knew and protect our families and loved ones.

The Centers for Disease Control and Prevention (CDC), North Carolina Department of Health and Human Services (NCDHHS), and UNC Health recommend all those who are eligible receive a COVID-19 vaccine even if you have previously tested positive for COVID-19. We pledge equal access no matter race, ethnicity, or economic status, and vaccine administration details will be shared widely, once confirmed.


[1] Fact Sheet: Explaining Operation Warp Speed, November 30, 2020

[2] U.S. Food & Drug Administration, What We Do, March 28, 2018

[3] U.S. Food & Drug Administration, Vaccine Development 101, November 20, 2020

[4] U.S. Food & Drug Administration, FDA Vaccine Facts, November 27, 2020

[5] Fact Sheet: Explaining Operation Warp Speed, November 30, 2020

[6] U.S. Food & Drug Administration, Vaccine Development 101, November 20, 2020

[7] Fact Sheet: Explaining Operation Warp Speed, November 30, 2020

[8] Pfizer, Pfizer and Biontech Conclude Phase 3 Study of Covid-19 Vaccine Candidate, Meeting All Primary Efficacy Endpoints November 18, 2020

[9] Moderna, Moderna Announces Primary Efficacy Analysis in Phase 3 COVE Study for Its COVID-19 Vaccine Candidate and Filing Today with U.S. FDA for Emergency Use Authorization, November 30, 2020

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