COVID-19 Vaccines: Additional Dose and Boosters 

There are two different ways to consider the need for additional vaccine doses in an individual or population. Both are currently components of the Centers for Disease Control and Prevention (CDC) guidance related to COVID-19.

What is a booster versus an additional dose?

  • Additional dose: An additional dose refers to a vaccine dose that is given to an individual when the primary dose may not result in enough of an immune response (antibodies needed).  Studies such as CORALE-IBD, PREVENT-COVID, ICARUS and HERCULES IBD have shown that the vast majority of patients with IBD are seropositive post immunization. 

  • Booster dose: A booster dose refers to a vaccine dose that is given to an individual if the primary dose did result in enough of an immune response (antibodies needed), but is likely to decrease over time.   (we should clarify that if someone was vaccinated in the late spring and has recently received a booster.  That should count as a booster

Who is eligible for either—or both? 

Eligibility requirements may be updated regularly by the CDC. Please check back for updates. 

For IBD patients, an additional dose may be considered for patients who are immunocompromised as defined by those receiving these immune therapies (thiopurines (azathioprine, 6-mercaptopurine, Azasan, Imuran, Purinethol), methotrexate (Trexall), prednisone, anti-TNF therapies including infliximab (Remicade, Inflectra, Remsima), adalimumab (Humira), certolizumab pegol (Cimzia), and golimumab (Simponi)). 

Patients receiving vedolizumab (Entyvio) or ustekinumab (Stelara) are not considered immunocompromised

Although studies in IBD have not shown an insufficient immune response to the vaccine, they are certainly eligible based on guidance from the CDC.  We encourage patients to discuss the need for additional dose and/or booster with their doctor. 

Booster dose: The CDC and FDA have authorized boosters for all adults age 12 and older, 5 months after an mRNA vaccine or 2 months after Johnson & Johnson vaccine.

Do IBD patients need an additional dose? 

Most IBD patients are not considered immunocompromised and ongoing research is showing that patients develop the sufficient antibodies intended from the COVID-19 vaccines. If you are taking immune therapies as outlined above, you should consider your level of risk and discuss with your doctor whether or not you need an additional dose of the vaccine (mRNA only). Immune suppressing therapies include the following:  

Remember, an additional dose is intended for those who have weakened immune systems. This is different than a booster dose which may be recommended within a longer timespan for a broader population who did mount an appropriate immune response. 

Can I mix and match doses? 

The FDA updated its approvals of the COVD-19 vaccines to allow for a mix-and-match approach to booster doses. People who had received the Johnson & Johnson vaccine may receive a booster dose from the other available vaccines, such as a dose of the Pfizer vaccine or a half dose of the Moderna vaccine. Patients who receive the initial series of the mRNA vaccines may decide to have a booster dose of another, including Johnson & Johnson. More information can be found in the following FDA update and summarized below:


Primary and additional primary doses vaccine manufacturer

Age of recipient (years)

Number of doses in primary series (interval between doses)

Additional primary dose in immunocompromised people (interval since 2nd dose)

Interval between last primary (including additional) to booster dose



2 (21 days)

Not recommended

Booster not recommended



2 (21 days)

1 (≥28 days)

≥ 5 months



2 (21 days)

1 (≥28 days)

≥ 5 months



2 (28 days)

1 (≥28 days)

≥ 5 months 



1 (Not applicable)

Not applicable

≥ 2 months

If I received an additional dose, will I need a booster (total of four doses)? 

According to the CDC, IBD patients who are immunocompromised (as defined above) and who received an mRNA vaccine as their primary dose are eligible to receive an additional dose of Pfizer BioNTech and Moderna. This can then be followed by a booster shot of the Pfizer BioNTech, Moderna, or Johnson & Johnson vaccine at least six months after their additional dose, for a total of four doses. 

If an immunocompromised person with IBD (as defined above) who originally received a Johnson & Johnson vaccine then opt with their doctor to receive an additional dose, this second shot can be a Pfizer or Moderna dose, and would need to be done at least two months after the initial dose of Johnson & Johnson. Please also note that IBD patients who had an initial dose of the Johnson & Johnson vaccine should not be given a third dose of any COVID-19 vaccine until further guidance is provided by the CDC. 

Patients should discuss their risks and concerns with their doctor to make a decision on the most appropriate choice for them.  


Last updated: 1/13/22