Frequently Asked Questions about Booster doses

The CDC recommends that everyone who is eligible stay up-to-date on vaccinations by getting an updated booster dose at least 2 months after their last COVID-19 shot—either since their last booster dose, or since completing their primary series. Pfizer’s and Moderna’s updated vaccines are available for individuals as young as 6 months. The CDC expanded the use to the youngest group of children (age 6 months to 5 years) on December 9, 2022.

These new boosters contain an updated bivalent formula that both boosts immunity against the original coronavirus strain and also protects against the newer Omicron variants that account for most of the current cases. Updated boosters are intended to provide optimal protection against the virus and address waning vaccine effectiveness over time.

Eligible individuals can get either the Pfizer or Moderna updated booster, regardless of whether their primary series or most recent dose was with Pfizer, Moderna, Novavax, or the Johnson & Johnson vaccine. As per the CDC’s recommendations, the new bivalent booster replaces the existing monovalent vaccine booster, therefore that vaccine will no longer be authorized for use as booster doses.

For children age 6 months to 5 years who get the Pfizer primary series, the updated bivalent vaccine will be used as the third dose in the series, rather than as a separate booster.

Novavax Booster: The Novavax vaccine is authorized as a first booster dose for adults, at least 6 months after completing primary vaccination with any authorized COVID-19 vaccine. Adults age 18 and older may choose to receive a Novavax booster instead of an updated Pfizer or Moderna booster if they are allergic to mRNA vaccines or they are otherwise inaccessible.

Updated December 9, 2022 

Yes, the CDC recommends that everyone age 5 and up should get an updated COVID-19 booster this fall to stay up-to-date on vaccinations. The same is true for people who completed their primary series or received one or two boosters: they should get an updated booster dose at least two months after their last shot.

For maximum effectiveness of the updated booster dose, individuals who recently had COVID-19 may consider delaying any COVID-19 vaccination, including the updated booster dose, by 3 months from the start of their symptoms or positive test.

Updated October 18, 2022 

No. The updated bivalent formula is in use only for COVID-19 booster doses, and not for initial vaccination. The best way to protect yourself from getting severely ill from COVID-19 is to get vaccinated. The CDC recommends that currently unvaccinated people get their primary series (the initial two doses of either the Pfizer, Moderna, or Novavax vaccines, or one dose of the Johnson & Johnson vaccine), and then wait at least two months to get the updated Pfizer or Moderna booster dose. Adults age 18 and older also have the option to receive a Novavax booster instead of an updated Pfizer or Moderna booster if they are unable to receive mRNA vaccines and haven’t previously received any booster dose.

Updated October 31, 2022 

On December 9, 2022 the CDC expanded the use of Pfizer and Moderna’s updated (bivalent) COVID-19 vaccine for children as young as 6 months.

  • Pfizer: For children age 6 months to 5 years who get the Pfizer primary series, the updated bivalent vaccine will be used as the third dose in the series, rather than as a separate booster. Children and teens age 5 and up should get the updated booster at least 2 months after they finish their 2-dose primary series.
  • Moderna: Children and teens age 6 months and up should get the updated Moderna booster at least 2 months after they finish their 2-dose primary series.

For more information about the vaccine and booster dose schedule, see: Pediatric Vaccines.

Updated December 9, 2022 

Booster doses are common for many vaccines, and over time, booster doses may need to be updated to provide optimal protection against new variants of the virus. The scientists and medical experts who developed the COVID-19 vaccines continue to watch for waning immunity, how well the vaccines protect against new mutations of the virus, and how that data differ across age groups and risk factors. 

To date, booster doses have worked well in extending the protection of the vaccine against serious illness, but have been somewhat less effective in boosting immunity against new variants of COVID-19 compared to the original strain. The updated booster dose formula is designed to protect against original strains of the virus, as well as Omicron variants that account for the majority of current new infections.

The latest CDC recommendations on booster doses help to ensure more people across the U.S. are better protected against COVID-19. The best way to protect yourself from COVID-19 is to get vaccinated and boosted if eligible. Vaccination and boosting is particularly important for individuals more at risk for severe COVID-19, such as older people and those with underlying medical conditions.

Updated September 2, 2022 

Yes. Eligible individuals can get either the Pfizer or Moderna updated booster, regardless of whether their primary series or most recent dose was with Pfizer, Moderna, Novavax, or the Johnson & Johnson vaccine. The Novavax vaccine is also authorized as a first booster dose for adults who are unable to get mRNA vaccines, at least 6 months after completing primary vaccination with any authorized COVID-19 vaccine

Updated October 31, 2022 

A booster dose is given after a complete vaccine series to provide additional protection against a vaccine’s effectiveness has decreased over time, while an additional dose is given to people with compromised immune systems to improve their response to the initial vaccine series. 

People with compromised immune systems may have a reduced ability to respond to vaccines, and having a weakened immune system can increase the risk of becoming severely ill from COVID-19. The CDC recommends that immunocompromised people who received the Pfizer or Moderna vaccine get an additional dose at least 28 days after their second shot. Data show that an additional dose of the Pfizer or Moderna vaccines helps to increase protection for this group. 

Patients who are immunocompromised should consult with their health care provider to discuss additional precautions and any questions they have about protecting themselves from COVID-19.

Updated February 28, 2022 

Messaging Resources about Booster doses

Misinformation Alerts about Booster doses

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