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Vaccine supplies at UNC Health are very limited. We are aware of the concern this is causing and are working hard to administer as many vaccines as possible. Please note that limited vaccine supply will not affect our ability to provide a second dose if you have already received your first dose. Learn more.

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Long-term data is not yet available, but clinical trials show vaccines are safe and effective.

The rollout of COVID-19 vaccines is a big milestone in our return to normal. Clinical trials show that the Pfizer and Moderna coronavirus disease 2019 (COVID-19) vaccines are about 95 percent effective at preventing people from getting sick with COVID-19.

But is there any long-term data about safety and effectiveness?

First, it’s important to know that the COVID-19 vaccine trials have been through every stage of clinical trials that would normally take place for a vaccine. The U.S. Food and Drug Administration (FDA) followed all required steps, and the CDC and the Advisory Committee on Immunization Practices (ACIP) have been actively involved in the evaluation process.

“It is very important to understand that it is just not possible to get a vaccine into humans without doing all the necessary steps,” says Dr. Gay. “It is a requirement that the FDA review a series of data initially in animal data, then phase one, then phase two, before we get to a phase three study.” An independent Data and Safety Monitoring Board also reviews all data and reports findings to the National Institute of Allergy and Infectious Diseases.

That said, we do not know the long-term ability of COVID-19 vaccines to prevent infection at this time. It is possible that you will need additional doses (boosters) of the vaccine in the future similar to the way the flu vaccine works.

Researchers will continue to follow the vaccine study participants to determine how long the vaccines might be effective.

“The reason to follow people for 12 months to two years after receiving the COVID-19 vaccines is because we want to know what the durability of the immune response would be, meaning, is this a similar scenario to influenza where we might have to give a booster vaccine after one year or after two years?” Dr. Gay says.

Due to the urgency of the crisis, long-term side effects are not as well understood as in a typical circumstance, however, UNC Health is not aware of long-term side effects of COVID-19 vaccines at this time. According to leading experts at UNC Health and across the county, the vast majority of long-term side effects appear within 45 days, and there has been more than sufficient time for research to evaluate this in studies.

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