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7 questions about COVID-19 vaccines

A healthcare worker in a mask and face shield touches the shoulder of a masked patient.

Many aspects of the COVID-19 pandemic are unprecedented. One of those is the ongoing effort to quickly develop and deliver safe and effective vaccines against the virus that causes COVID-19.

Here are answers to some questions you may have about these vaccines.

Q. How many vaccines are there?

A. Three vaccines have already been authorized for use in the U.S. One is made by Pfizer, one by Moderna and another by Johnson & Johnson (J&J). Millions of people have received them so far. 

Multiple other vaccines are still being developed in the U.S. Several of those are in Phase 3 clinical trials. That is typically the final stage of the vaccine trial process before a vaccine may be submitted to the U.S. Food and Drug Administration (FDA) for review. 

Q. Why are so many vaccines being developed at once?

A. The vaccines work in different ways. Some are based on using dead viruses to stimulate immunity. (This is the same method used for the flu shot and many other vaccines.) Others use just a part of the virus, like the spike protein from its surface. And still others are based on newer methods using the virus's genetic material—either on its own or inserted into another harmless virus. Exploring different approaches gives a better chance of finding safe and effective vaccines.

Q. How do we know the vaccines are safe?

A. A vaccine must be shown to be safe and effective before it can be offered to the public. That's what the clinical trial process is for. FDA only authorizes a vaccine for use if it determines that the benefits outweigh the risks.

The vaccines currently in use had excellent safety records in clinical trials. The most common side effects are mild, like a fever or soreness at the injection site. While some people have experienced allergic reactions to the vaccines, the overall number is small. And vaccine providers are taking steps to monitor and treat any problems.

FDA and the Centers for Disease Control and Prevention (CDC) also continue to monitor vaccines for safety after they are in use. You can help by signing up for CDC's v-safe program after you get a shot.

Q. How well do the vaccines work?

A. The Pfizer vaccine was 91% effective at preventing COVID-19 in clinical trials. Moderna's vaccine was 94.1% effective. J&J's vaccine was about 66.1% effective overall in its U.S. trial and 85% effective against severe disease. All these numbers are very good.

The Pfizer and Moderna vaccines require two doses, given several weeks apart, to provide full protection. The J&J vaccine is given in a single dose.

Q. How much does a vaccine cost?

A. The vaccines themselves are free. Some providers may charge a low fee for giving the shot. But most health plans will cover it. So there should be no cost to the person getting the vaccine. No one can be denied a vaccine if they can't afford to pay.

Q. When can I get vaccinated?

A. Everyone 12 and older in the U.S. is now eligible to get a COVID-19 vaccine. Check with your local health department to find out how to make an appointment.

Q. After I get a vaccine, can I stop social distancing and wearing a mask?

A. You can drop your mask and stop distancing in some instances. But if COVID-19 rates are high in your area, you should keep masking up in public indoor spaces. And you should follow all local laws and regulations. For instance, you still need to wear a mask on public transportation and if required by local businesses.

To learn more about specific vaccines, visit our Coronavirus health topic center.

Reviewed 8/19/2021

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