What You Need to Know
If you receive a Pfizer-BioNTech or Moderna COVID-19 vaccine, you will need 2 initial shots to complete the primary series.
CDC does not recommend mixing products for a two dose primary vaccine series or an additional primary dose. If you received a Pfizer-BioNTech or Moderna COVID-19 vaccine, you should get the same product when you need a second shot or additional primary dose. However, mixing and matching COVID-19 vaccines is allowed for booster shots for people ages 18 years and older.
You should get your second shot even if you have side effects after the first shot, unless a vaccination provider or your doctor tells you not to get it.
If you have a weakened immune system due to other diseases or medications, you can receive a COVID-19 vaccine if you have not had a severe allergic reaction to any of the ingredients in the vaccine.
People with moderately or severely compromised immune systems ages 12 years and older who completed their Pfizer-BioNTech COVID-19 vaccine primary series and ages 18 years or older who completed their Moderna COVID-19 vaccine primary series should get an additional primary dose at least 28 days after their second shot.
Everyone ages 16 years and older who completed their COVID-19 vaccine primary series can get a booster shot. Pfizer-BioNTech or Moderna (mRNA COVID-19 vaccines) are preferred in most situations. Although mRNA vaccines are preferred, J&J/Janssen COVID-19 vaccine may be considered in some situations.
Timing of Your Second Shot
The timing between your first and second shots depends on which vaccine you received. If you received the:
Get your second shot 3 weeks (or 21 days) after your first
Get your second shot 4 weeks (or 28 days) after your first
Scheduling Your Second Shot:
Planning for your second shot is important.
If you need help scheduling your vaccination appointment for your second shot, contact the location that set up your first appointment.
If you are having trouble or have questions about using a vaccination management or scheduling system, reach out to the organization that enrolled you in the system. This may be your state or local health department, employer, or vaccination provider.
Scheduling an appointment for your second shot at the time you get your first shot is recommended, but not required.
If you need to get your second shot in a location that is different from where you received your first shot (for example, if you moved to a different state or attend school in a different state), there are several ways you can find a vaccine provider for your second dose.
Your CDC COVID-19 Vaccination Record Card and Your Second Shot
At your first vaccination appointment, you should have received a CDC COVID-19 Vaccination Record card that tells you what COVID-19 vaccine you received, the date you received it, and where you received it.
Bring your vaccination card with you to your second shot appointment so your provider can fill in the information about your second dose.
If you did not receive a CDC COVID-19 Vaccination Record card at your first appointment, contact the vaccination provider site where you got your first shot or your state health department to find out how you can get a card.
Learn more about what to do if you need a copy of your CDC COVID-19 Vaccination Record card.
After Getting Your Second Shot
Cases of myocarditis and pericarditis in adolescents and young adults have been reported more often after getting the second dose than after the first dose of one of the two mRNA COVID-19 vaccines, Pfizer-BioNTech or Moderna. These reports are rare and the known and potential benefits of COVID-19 vaccination outweigh the known and potential risks, including the possible risk of myocarditis or pericarditis.
Use v-safe on your smartphone to tell CDC about any side effects after getting the COVID-19 vaccine. If you enter your second shot in your v-safe account, the system will send you daily health check-ins. Please note that v-safe is not automatically notified when you receive a second shot of vaccine, so you must enter the information yourself.
When You Are Fully Vaccinated
People are considered fully vaccinated:
2 weeks after their second shot in a 2-dose series, like the Pfizer-BioNTech or Moderna vaccines, or
2 weeks after a single-shot vaccine, like Johnson & Johnson’s Janssen COVID-19 Vaccine
You are not fully vaccinated if:
It has been less than 2 weeks since your single-dose shot
It has been less than 2 weeks since your second shot of a two-dose vaccine
You haven’t received your second dose of a two-dose vaccine
Everyone ages 16 years and older, who is fully vaccinated, can get a COVID-19 vaccine booster shot. Learn more about booster shots.