Frequently Asked Questions (FAQ)
Do I need a booster?
Yes. The protection COVID-19 vaccines provide decreases over time, especially for certain groups of people.
- Recent data suggest their effectiveness at preventing infection or severe illness wanes over time, especially in people ages 65 years and older.
The emergence of the variants further emphasizes the importance of vaccination, boosters, and prevention efforts needed to protect against COVID-19.
CDC recommends everyone ages 5 years and older stay up to date with their vaccines, which includes getting boosters when eligible, for the best protection against COVID-19
- Data show that an mRNA booster increases the immune response, which improves protection against getting a serious COVID-19 infection.
Learn more about COVID-19 vaccine recommendations, including recommendations for people who are moderately or severely immunocompromised. Use CDC’s COVID-19 Booster Tool to learn if and when you can get boosters to stay up to date with your COVID-19 vaccines.
If I received a Johnson & Johnson vaccine, and a J&J booster, are additional booster recommended?
People (except those who are moderately or severely immunocompromised) who first received a J&J/Janssen COVID-19 vaccine and got it again for their booster may also receive a booster of an mRNA COVID-19 vaccine (Pfizer-BioNTech or Moderna). Get the mRNA booster at least 4 months after the most recent J&J/Janssen booster.
- One CDC study found that adults who received the J&J/Janssen COVID-19 vaccine as both their primary and booster had lower levels of protection against COVID-19-associated emergency department and urgent care visits during Omicron compared to adults who received an mRNA COVID-19 booster.
Home many doses of COVID-19 vaccine will I need to complete my primary series?
The number of vaccine doses you need to complete your primary series depends on which vaccine you receive.
- Two doses of Pfizer-BioNTech vaccine 3–8* weeks apart, or
- Two doses of Moderna vaccine 4–8* weeks apart, or
- One dose of Johnson & Johnson’s Janssen (J&J/Janssen) vaccine.
*Talk to your healthcare or vaccine provider about the timing for the second dose in your primary series. You should not get the second dose early.
People who are moderately or severely immunocompromised may have a different immune response following COVID-19 vaccination. Please see specific COVID-19 vaccination guidance for people who are moderately or severely immunocompromised.
If I miss a dose, do I need to start over?
No. If you receive your second dose of a COVID-19 vaccine at any time after the recommended date, you do not have to restart the vaccine series. This guidance might be updated as more information becomes available.
Learn more about staying up to date with your COVID-19 vaccines.