1. Home
  2. Resources
  3. Boosters

Primary Series and Boosters

The CDC now recommends that people whose immune systems are moderately to severely compromised should receive a 3-dose mRNA vaccine primary series followed by 2 booster doses for a total of 5 doses.

A 3-dose primary mRNA COVID-19 vaccine series is recommended for people ages 5 years and older who are moderately or severely immunocompromised, followed by 2 booster doses in those ages 12 years and older or 1 booster dose for those 5-11 years old.

In most situations, Pfizer-BioNTech (Comirnaty) or Moderna (Spikevax) COVID-19 Vaccines are preferred over the Janssen COVID-19 Vaccine for primary and booster vaccination.

A booster dose of COVID-19 vaccine is recommended for everyone ages 5 years and older. A second booster dose is also recommended for people who are 50+, 12+ and moderately or severely immunocompromised, or who are 18-49 and received 2 doses of the Janssen (J&J) vaccine are eligible for a second booster.

Frequently Asked Questions

What is the difference between the primary series, additional dose, and booster dose?
Primary series:

• For most people, 2-dose series of an mRNA COVID-19 vaccine (Pfizer-BioNTech and Moderna) or a single dose of Janssen Vaccine.
• For people who are moderately or severely immunocompromised, a 3-dose series of an mRNA COVID-19 vaccine or a single dose
of Janssen COVID-19 Vaccine.

Additional dose: A subsequent dose of vaccine administered to people who likely did not mount a protective immune response after initial vaccination. People who are moderately or severely immunocompromised and who received Janssen COVID-19 Vaccine for their primary series should receive an additional dose.

Booster dose: A subsequent dose of vaccine administered to enhance or restore protection which might have waned over time after primary series vaccination.

The CDC now recommends an additional dose for certain groups of people with weakened immune systems. Some examples below.

• Been receiving active cancer treatment for tumors or cancers of the blood
• Received an organ transplant and are taking medicine to suppress the immune system
• Received a stem cell transplant within the last 2 years or are taking medicine to suppress the immune system
• Moderate or severe primary immunodeficiency (such as DiGeorge syndrome, Wiskott-Aldrich syndrome)
• Advanced or untreated HIV infection
• Active treatment with high-dose corticosteroids or other drugs that may suppress your immune response

People should talk to their healthcare provider about their medical condition, and whether getting an additional dose is appropriate for them. See criteria here.

All people ages 5 years and older should receive an age-appropriate booster dose and formulation of COVID-19 vaccine, even if they were age 4 years or younger at the time of the primary series. Currently, COVID-19 vaccines are not authorized for a booster dose for children ages 4 years and younger.

An mRNA COVID-19 vaccine is preferred over the Janssen COVID-19 Vaccine for booster vaccination. In people ages 5–17 years, only Pfizer-BioNTech COVID-19 Vaccine can be used. The recommended interval for the first booster dose is based on the product received for the primary series. In most people, the interval is:

• At least 5 months after mRNA 2-dose primary vaccination or
• At least 2 months after Janssen single dose primary vaccination
• See guidance for those who are moderately or severely immunocompromised below

The recommended interval for second booster dose is at least 4 months following the receipt of their initial booster dose of any authorized or approved COVID-19 vaccine among the following populations:

people who are 50+, 12+ and moderately or severely immunocompromised, or who are 18-49 and received 2 doses of the Janssen (J&J) vaccine are eligible for a second booster.

Among those who are eligible, the following people may consider a second booster dose as soon as possible:

  • People with certain underlying medical conditions that increase the risk of severe COVID-19 illness
  • People who are moderately or severely immunocompromised
  • People who live with someone who is immunocompromised, at increased risk for severe disease, or who cannot be vaccinated due to age or contraindication
  • People at increased risk of exposure to SARS-CoV-2, such as through occupational, institutional, or other activities (e.g. travel or large gatherings)
  • People living or working in an area where the COVID-19 community level is medium or high

Among those who are eligible, the following people may consider waiting to receive a second booster dose:

  • People with SARS-CoV-2 infection within the past 3 months
  • People who may be hesitant about getting another recommended booster dose in the future, as a booster dose may be more important in the fall and/or if a variant-specific vaccine is needed

Pfizer-BioNTech Booster Shots Recommendations as of 5/20/22

1st Booster Dose:

Who should get their first booster dose?
Everyone 5 years or older.

When should I get my first booster dose?
At least 5 months after completing your primary COVID-19 vaccination series.*

*Those who are moderately or severely immunocompromised are eligible at least 3 months after completion of the primary COVID-19 vaccination series.

2nd Booster Dose:

Who should get their second booster dose?

  • Everyone 50 years or older
  • Individuals 12 years of age or older who are moderately or severely immunocompromised
  • Individuals 18 years of age or older who received a primary vaccine and booster dose of Johnson & Johnson’s Janssen COVID-19 vaccine at least 4 months ago

Which booster should you get?
Pfizer-BioNTech or Moderna (mRNA COVID-19 vaccines) are preferred in most* situations.
People 5-17 years old may only get a Pfizer-BioNTech COVID-19 booster.

Moderna Booster Shots Recommendations as of 3/29/22

Who should get a booster dose?
Adults 18 years or older.

When should I get my booster dose?
At least 5 months after completing your primary COVID-19 vaccination series.*

*Those who are moderately or severely immunocompromised are eligible at least 3 months after completion of the primary COVID-19 vaccination series.

Which booster should you get?
Pfizer-BioNTech or Moderna (mRNA COVID-19 vaccines) are preferred in most* situations.

Johnson & Johnson’s Booster Shots Recommendations as of 3/29/22

1st Booster Dose:

Who should get their first booster dose?
Adults 18 years or older.

When should I get my first booster dose?
At least 2 months after completing your primary COVID-19 vaccination series.

2nd Booster Dose:

Who should get their second booster dose?

  • Everyone 50 years or older
  • Individuals 12 years of age or older who are moderately or severely immunocompromised
  • Individuals 18 years of age or older who received a primary vaccine and booster dose of Johnson & Johnson’s Janssen COVID-19 vaccine at least 4 months ago

Which booster should you get?
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.

For the most updated CDC Booster Shot recommendations, click here.

There is no required proof outside of a self-attestation. A self-attestation is a statement indicating that you have self-determined that you are eligible to receive an additional dose or second booster dose of a COVID-19 vaccine.

Self-attestation forms are available at every County-run vaccine clinic. To view the self-attestation, please see the following:

All COVID-19 vaccines are approved for booster doses.

Pfizer and Moderna are approved for additional doses.

There are now booster recommendations for all three available COVID-19 vaccines in the United States. Eligible individuals 18 years of age and older may choose which vaccine they receive as a booster dose. Some people may have a preference for the vaccine type that they originally received, and others may prefer to get a different booster. CDC’s recommendations now allow for this type of mix and match dosing for booster shots.

Per the Western States Scientific Safety Review Workgroup:

“Individuals who have previously received an initial series of any of the three COVID-19 vaccines currently approved or authorized for use in the United States are eligible for a booster dose. The Workgroup supports CDC’s decision that individuals eligible for a booster may receive either the same or a different COVID-19 vaccine as a booster dose, depending on advice from a health care provider, individual preference, availability or convenience.”

Please refer to the following media statement from the CDC on Booster Shot Mixing and Matching and the Western States Scientific Safety Review Workgroup statement.

Contact your provider directly to confirm if you need to bring your vaccine card.

If you make an appointment at an SB County Vaccine Clinic or special pop-up event please bring your vaccine card.

If you have lost your vaccine card please refer to this website: https://sbcovid19.com/vaccinecards/.

Children ages 5 through 11 years who are moderately or severely immunocompromised should receive a primary series of 3 doses of Pfizer-BioNTech COVID-19 vaccine. A booster is not recommended for this age group at this time.

People ages 12 years and older who are moderately or severely immunocompromised should receive a total of 5 doses of COVID-19 vaccine. The 5 doses are made up of a primary series of 3 doses of an mRNA COVID-19 vaccine, plus 2 boosters of an mRNA COVID-19 vaccine.

People ages 18 years and older who are moderately or severely immunocompromised and received the 1 dose Johnson & Johnson’s Janssen COVID-19 vaccine should get a second dose of either Pfizer-BioNTech or Moderna COVID-19 vaccine (mRNA COVID-19 vaccines). They should also receive a booster—for a total of 3 doses. For those who have received the 1 dose Johnson & Johnson’s Janssen COVID-19 vaccine, they may also receive a second booster using an mRNA COVID-19 vaccine.

FDA Authorizations for Healthcare Providers and Fact Sheets for Patients

Pfizer-BioNTech Fact Sheet:
For Recipients and Caregivers

Moderna Fact Sheet:
For Recipients and Caregivers

Janssen Fact Sheet:
For Recipients and Caregivers

COVID-19 Boosters California Department of Public Health (CDPH) Recommendation

5/20/2022 Updates to follow