Frequently Asked Questions

The U.S. Food and Drug Administration (FDA) has granted Emergency Use Authorizations (EUA) for two COVID-19 vaccines which have been shown to be safe and effective as determined by data from the manufacturers and findings from large clinical trials.
These data demonstrate that the known and potential benefits of this vaccine outweigh the known and potential harms of becoming infected with the coronavirus disease 2019 (COVID 19).
As people get vaccinated, CDC, FDA, and other federal partners will use the following existing, robust systems and data sources to conduct ongoing safety monitoring.
CDC has expanded safety surveillance through new systems and additional information sources, as well as by scaling up existing safety monitoring systems.
Learn more about the monitoring systems for the general public, members of the military, veterans, and tribal nations.

Before the U.S. Food and Drug Administration (FDA) determines whether to approve a vaccine or authorize a vaccine for emergency use, clinical trials are conducted to determine how well it works. This is known as effectiveness.
After FDA approves a vaccine or authorizes a vaccine for emergency use, it continues to be studied to determine how well it works under real-world conditions. CDC and other federal partners will be assessing COVID-19 vaccine effectiveness under real-world conditions.
Clinical trials provide data and information about how well a vaccine prevents an infectious disease and about how safe it is. So far the clinical trials have shown that vaccines are effective.
Experts are evaluating the effectiveness of the vaccines using case-control studies, cohort studies, screening methods, and ecologic analyses.

Before vaccination:
- When you get the vaccine, you and your healthcare worker will both need to wear masks that cover your nose and mouth. Stay 6 feet away from others while inside and in lines.
When You Get Vaccinated:
- You should receive a vaccination card or printout that states the vaccine received, the dated received, and where you received it.
- You should also get details of the specific COVID-19 vaccine fact sheet to understand the risks and benefits.
- All people that get the vaccine should be monitored on-site.
After Vaccination:
- With most COVID-19 vaccines, you will need 2 shots in order for them to work. Get the 2nd shot even if you have side effects after the 1st one, unless a vaccination provider tells you not to get a second shot.

If you get a COVID-19 vaccine and you think you might be having a severe allergic reaction after leaving the vaccination site, seek immediate medical care by calling 911.
To get more details, please talk to your healthcare provider or access the CDC's recommendations below.

COVID-19 vaccination will help protect you from getting COVID-19.
You may have some side effects, which are normal signs that your body is building protection. These side effects may affect your ability to do daily activities, but they should go away in a few days.
To get more details, please talk to your healthcare provider or access the CDC's recommendations below.

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