Vaccine-Booster-QA COVID-19 Vaccine Booster Questions & Answers

COVID-19 Vaccine Booster Questions & Answers

Updates as of September 3, 2022:

  • Aligned with the U.S. Centers for Disease Control and Prevention (CDC) and the Federal Food and Drug Administration (FDA) to grant emergency use authorization (EUA) of the Pfizer-BioNTech bivalent booster for everyone 12 years and older, and Moderna bivalent booster for everyone 18 years and older.

Who is eligible for booster or additional doses?

Booster and additional doses are recommended or allowed for the following ages upon completion of a primary vaccination series. For more information on Booster or Additional Doses, see Related Materials at the top of the page. 

What is the difference between boosters and additional doses for immunocompromised individuals?

A booster dose is a dose of vaccine that is needed when a person's level of immunity has decreased over time. Booster doses are very common and are a normal part of most vaccine series.

An additional dose for immunocompromised individuals aged 6 months or older is necessary as an initial primary vaccine series is likely to be insufficient, and an additional dose can increase a person's immune response. 

For more information on Booster and Additional Doses, see Related Materials at the top of the page.

When should I receive a booster dose?

Everyone should receive a booster dose following completion of their primary vaccine series, if eligible. 

For more information on eligibility, see Related Materials at the top of the page.

When were booster doses made available in California?

In September of 2021, Pfizer booster doses were authorized for use in California for people aged 12 years and older.

In October of 2021, Moderna booster doses were authorized for use in California for people aged 18 years and older.

In March of 2022, Pfizer and Moderna booster doses were expanded for use in California to people in vulnerable groups.

In May of 2022, Pfizer booster doses were expanded for use in California for children aged 5-11 years.

In August of 2022, Pfizer and Moderna bivalent booster doses were authorized for use in California for everyone aged 12 years+ and 18 years+, respectively.

Can I receive a booster dose before the recommended time frame?

No, booster doses are authorized for a specific time frame based on the initial vaccine received and its corresponding research and data.

Is a booster dose the same amount of vaccine as doses in the original vaccine series?

The Pfizer and Johnson & Johnson booster doses are the same portion as the original vaccine received in the series, while the Moderna booster dose is half dosage compared to the original vaccine series.

How does someone find and receive a booster dose?

Booster doses are available through all current channels, including healthcare providers, clinics and neighborhood pharmacies. Californians can find a vaccine clinic or make an appointment online at My Turn website ( or by calling 833-422-4255.

Which vaccines are covered by the emergency use authorization for booster doses?

Pfizer and Moderna COVID-19 vaccines have been granted an EUA to allow for booster vaccine doses for specific populations. Johnson & Johnson may be used in limited settings. Novavax is not eligible for booster doses at this time. 

For more information on Booster Doses, see Related Materials at the top of the page.

Can a person get a booster dose from a different manufacturer from their original series, or do they need to stay with the brand for their original supplier?

Yes, if in an eligible age group, the booster doses may be administered as a mix and match (heterologous) following completion of a primary vaccine series. Eligibility requirements and dosing intervals remain the same regardless of which booster dose is selected.


  • If aged 12 years or older, those who received Moderna as their primary series, should receive the Updated Booster dose of Pfizer.
  • If aged 18 or older, those who received Johnson & Johnson for their primary series, should receive the Updated Booster dose of Moderna or Pfizer.

Can I get multiple boosters?

Yes, if you are in an eligible age group. Please reference "Who is eligible for booster vaccinations?" to see if you meet the requirements.

What is the current CA Public Health Order regarding boosters?

Find important state guidance on activities related to COVID-19 by topic. Sign up to receive alerts for updates to California state public health officer orders and public health mandates related to COVID-19 in 14 languages.

Will digital vaccine records be updated to show that individuals have received a booster dose?

Yes, the Digital COVID-19 Vaccine Record will be updated and will show that a booster vaccine dose has been administered. However, your previously saved vaccine record will not automatically update, so a new version will need to be re-downloaded to reflect that you have received an additional dose and/or booster dose.

We recommend waiting fourteen days for your new dose to show up in the California Immunization Registry.

If I get a booster dose, will it show on my digital vaccine record?

The QR code on your digital vaccine record does not automatically update. If you receive a booster dose of the COVID-19 vaccine, you'll have to get a new QR code through the Digital COVID-19 Vaccine Record portal.

We recommend waiting fourteen days for your new dose to show up in the California Immunization Registry.

Will an antibody or other test show whether I need a booster dose?

We do not recommend using antibodies or any other tests to determine protection from the virus at this time. There is significant variability from one antibody test to another, and further studies are needed to ensure correlation between antibody levels and degree of protection from COVID-19 and its variants.

Does receiving a booster eliminate the need for further harm-reduction precautions?

To prevent severe illness and death, a comprehensive approach to harm-reduction is needed. In addition to receiving all eligible doses, it is imperative that we keep all Californians safe by staying SMART: masking up in large crowds or when feeling sick, staying aware of rising cases in your area, and getting tested with known or suspected exposure.

Should pregnant or recently pregnant individuals receive a booster dose?

Yes, people who are pregnant are eligible and encouraged to receive a booster dose. People who are pregnant or recently pregnant are more likely to get severely ill with COVID-19 compared with people who are not pregnant. Find more resources on CDPH's Pregnancy and COVID-19 Vaccines website.

How is California verifying people are getting booster vaccine doses within the recommended time frame mark and not jumping the queue?

California is using self attestation to confirm eligibility for a booster dose. There is no verification process required to confirm eligibility, though some providers may ask for additional confirmation or eligibility such as verification of age or occupation. California has ample supply to ensure all eligible Californians will have access to the vaccine.

How do we know booster doses are safe?

Just as with the initial vaccine series, booster doses went through rigorous scientific review to confirm the safety and efficacy of using subsequent doses to protect against COVID-19. This data was reviewed and compiled from global researchers before being authorized by the FDA.

What side effects should be expected after receiving a booster dose?

People who have received booster doses have reported similarly mild side effects as compared to the side effects they experienced when receiving their initial vaccine dose. They reported a sore arm at the injection site and/or mild flu-like symptoms. These reactions are normal and demonstrate that your body is rebuilding immunity to COVID-19. 

Originally published on October 7, 2021