COVID-19 Vaccine Primary Series
The number of vaccine doses you need depends on which vaccine you receive.
- Two doses of Pfizer-BioNTech vaccine should be given 3 weeks (21 days) apart.
- Two doses of Moderna vaccine should be given 4 weeks (28 days) apart.
- Only one dose of Johnson & Johnson’s Janssen (J&J/Janssen) vaccine should be given.
If you receive a vaccine that requires two doses, you should get your second shot as close to the recommended interval as possible. You should not get the second dose earlier than the recommended interval.
COVID-19 vaccines are not interchangeable for your COVID-19 vaccine primary series. If you received a Pfizer-BioNTech or Moderna COVID-19 vaccine for your first shot, you should get the same product for your second shot.
Everyone ages 16 years and older can get a booster shot after they have completed their COVID-19 vaccine primary series. People ages 16 to 17 years old can get the Pfizer-BioNTech COVID-19 booster shot.
People ages 18 years and older have the option to either get the same COVID-19 vaccine product as their primary series, or to get a different COVID-19 vaccine. People may have a preference for the vaccine type that they originally received, or they may prefer to get a different booster. CDC’s recommendations now allow for this type of mix and match dosing for booster shots (Pfizer-BioNTech, Moderna, or J&J/Janssen) for people ages 18 years and older. You may consider the benefits and risks of each product and discuss with your healthcare provider which COVID-19 vaccine product is the most appropriate booster for you.
Currently, a booster shot is not recommended for children younger than 16 years old.
You should get a COVID-19 vaccine even if you already had COVID-19.
Getting sick with COVID-19 offers some protection from future illness with COVID-19, sometimes called “natural immunity.” The level of protection people get from having COVID-19 may vary depending on how mild or severe their illness was, the time since their infection, and their age. No currently available test can reliably determine if a person is protected from infection.
All COVID-19 vaccines currently available in the United States are effective at preventing COVID-19. Getting a COVID-19 vaccine gives most people a high level of protection against COVID-19 even in people who have already been sick with COVID-19.
Emerging evidence shows that getting a COVID-19 vaccine after you recover from COVID-19 infection provides added protection to your immune system. One study showed that, for people who already had COVID-19, those who do not get vaccinated after their recovery are more than 2 times as likely to get COVID-19 again than those who get fully vaccinated after their recovery.
People who were treated for COVID-19 with monoclonal antibodies or convalescent plasma or people who have a history of multisystem inflammatory syndrome in adults or children (MIS-A or MIS-C) may need to wait a while after recovering before they can get vaccinated. Talk to your doctor if you are unsure what treatments you received or if you have more questions about getting a COVID-19 vaccine.
We don’t know yet how long COVID-19 vaccine protection lasts. Recent studies show that protection against the virus may decrease over time. This reduction in protection has led CDC to recommend that everyone ages 18 years and older get a booster shot after completing their primary vaccination series.
People who received the Pfizer-BioNTech or Moderna COVID-19 vaccine for their primary series should get a booster shot at least 6 months after completing the primary series. People who received Johnson & Johnson’s Janssen COVID-19 vaccine should get a booster shot at least 2 months after getting their first shot.
At this time, CDC recommends getting only one COVID-19 booster shot. CDC continues to review evidence and will update guidance as more information is available.
Learn more about COVID-19 vaccine booster shots.
No. People with COVID-19 who have symptoms should wait to be vaccinated until they have recovered from their illness and have met the criteria for discontinuing isolation; those without symptoms should also wait until they meet the criteria before getting vaccinated. This guidance also applies to people who get COVID-19 before getting their second dose of vaccine.
People who have had a known COVID-19 exposure should not seek vaccination until their quarantine period has ended to avoid potentially exposing healthcare personnel and others during the vaccination visit. This recommendation also applies to people with a known COVID-19 exposure who have received their first dose of an mRNA vaccine but not their second.