About COVID-19 Vaccines

Several COVID-19 vaccines have been developed. Vaccines are made by different companies. Each may have some differences from the others. So far, vaccines made by Pfizer-BioNTech, Moderna, and Johnson & Johnson's Janssen are the only vaccines authorized for emergency use in the United States. Emergency use authorization of additional COVID-19 vaccines are expected to continue through 2021. As the U.S. Food & Drug Administration meets and reviews other COVID-19 vaccines, the agency will provide updates on vaccines authorized for emergency use. When new details become available, the County of San Diego will update the information provided on this website.

The Centers for Disease Control and Prevention (CDC) has information about the vaccines undergoing large-scale trials. Most of the vaccines in these trials require two doses. The first shot starts building protection. A second shot 3-4 weeks later adds to the protection and provides maximum effectiveness.

If you tested positive for COVID-19 and recovered, you should still get the vaccine. While there is likely some immunity following recovery lasting at least a few weeks, it is unclear how long that immunity lasts and how much protection you get. Vaccination of persons with known current SARS-CoV-2 infection should be deferred until the person has recovered from acute illness (if the person had symptoms) and until criteria have been met for them to discontinue isolation.

Any individuals in the community who have had a known COVID-19 exposure should not get vaccinated for COVID-19 until their quarantine period has ended to avoid potentially exposing healthcare professionals and other persons to the virus during their vaccination visit.

As the vaccines become available, you will still need to wear a mask and practice social distancing until enough people have been vaccinated and the virus gets under control. Vaccines have been shown to prevent infection. Studies are pending to see whether vaccines prevent spread of COVID-19.

See more CDC information about how the vaccine works.

Pfizer-BioNTech COVID-19 Vaccine Fact Sheets

Moderna COVID-19 Vaccine Fact Sheets

Janssen COVID-19 Vaccine Fact Sheets



Vaccines go through large clinical trials before the U.S. Food and Drug Administration authorizes them to be given to the public. 

After being vaccinated, you may experience some side effects. This is a normal response and indicates that the vaccine is working. Read more about what to expect after being vaccinated and helpful tips

You cannot get COVID-19 from the vaccine because the vaccines are not made with active SARS-CoV-2 virus.

The CDC has more on vaccine safety, including its new v-safe tool created for COVID-19 vaccines.