COVID-19: Additional Vaccine Dose for People who are Moderately to Severely Immunocompromised

People who are moderately to severely immunocompromised are recommended to get an additional dose of an mRNA COVID-19 vaccine (Pfizer or Moderna) no sooner than 28 days after their initial two-dose mRNA COVID-19 vaccine series.

Fully vaccinated people who are not moderately or severely immunocompromised do not need an additional vaccine dose of COVID-19 vaccine at this time.

Adult wearing a mask supporting: You Stop the Spread

People who received a Johnson & Johnson COVID-19 vaccine are not recommended to receive an additional dose at this time because of limited data. The Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA) are monitoring the data and will make recommendations as needed.

Who should get an additional dose?

The FDA has updated the emergency use authorizations (EUAs) for the Pfizer and Moderna COVID-19 vaccines to allow for additional doses to very specific groups of people. Only the following groups may get an additional dose of mRNA COVID-19 vaccine.

People who are immunocompromised

Individuals with specific medical conditions or receiving medical treatments that cause them to be moderately to severely immunocompromised are recommended to get an additional dose of Pfizer or Moderna COVID-19 vaccine. This includes people who have:

  • 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 two 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, alkylating agents, antimetabolites, transplant-related immunosuppressive drugs, cancer chemotherapeutic agents classified as severely immunosuppressive, tumor-necrosis (TNF) blockers, or other drugs that may suppress your immune response.

Immunocompromised people have a reduced ability to fight disease, a lower immune response to the original vaccine series compared to other fully vaccinated people, and are especially vulnerable to COVID-19 infection. An additional dose of vaccine can increase an immunocompromised person’s level of protection against COVID-19 infection and help reduce the likelihood of them spreading COVID-19 to others. In small studies, fully vaccinated immunocompromised people made up a large proportion of hospitalized “breakthrough cases,” and that suggests immunocompromised people are more likely to transmit the virus to household contacts.

Even though the additional dose will be important to help prevent COVID-19 hospitalizations and death, immunocompromised people may still have a reduced immune response after getting the additional dose of the mRNA COVID-19 vaccine. This means, it is still important for immunocompromised people to take continue to follow current prevention measures (like wearing a mask and physical distancing) even after their additional mRNA COVID-19 vaccine dose.

Talk to your health care provider about:

  • whether you need to get an additional dose.
  • whether you will need to pause your treatment or medication before or after getting an additional dose of the vaccine.

If you don't have a health care provider, call 211 or text COVID to 211-211. Language assistance is available.

People who live with or frequently interact with immunocompromised people should continue to follow current prevention measures and get an initial COVID-19 vaccine series, if they have not done so already, to protect themselves and others from COVID-19.


Frequently asked questions

What should immunocompromised people who received the Johnson & Johnson (Janssen) COVID-19 vaccine do?

At this time, only individuals with specific medical conditions or receiving medical treatments that cause them to be moderately to severely immunocompromised who received initially received an mRNA COVID-19 vaccine series (Pfizer or Moderna) are eligible for an additional dose.

The FDA and CDC are working to better understand the data on whether immunocompromised people who received the Johnson & Johnson (Janssen) COVID-19 vaccine also have an improved antibody response following an additional dose of the same vaccine.

The FDA and CDC are actively working to provide guidance on this issue.

Can you mix and match the mRNA vaccines?

The additional dose should be the same vaccine product as the initial two-dose mRNA COVID-19 vaccine series (Pfizer or Moderna). If you are 18 years or older and the mRNA COVID-19 vaccine product given for the first two doses is not available, you can get the other mRNA COVID-19 vaccine product that is available.

For example, if you received your first two doses of Pfizer COVID-19 vaccine but you cannot find a vaccine location that has Pfizer vaccine, you can get an additional dose of Moderna COVID-19 vaccine if you are 18 years or older. If you are immunocompromised and are younger than 18 years old, your additional dose has to be a dose of Pfizer COVID-19 vaccine.

What is an additional dose and how is it different from a booster dose?

An “additional dose” is recommended for people who may not have received adequate protection from their initial vaccine series. For example, studies show some people who have weakened immune systems don’t always build the same level of immunity after vaccination the way non-immunocompromised people do. People who are moderately to severely immunocompromised are recommended to get an additional dose of an mRNA COVID-19 vaccine (Pfizer or Moderna) to increase their immune response so they have protection against COVID-19.

A “booster dose” is a supplemental vaccine dose given to people when the immune response to a primary vaccine series is likely to have decreased over time. The need for and timing of a COVID-19 booster dose has not yet been established, and at this time, booster doses have not been recommended. The CDC and FDA continue to review evidence and data as it is available about whether or when booster doses for the broader U.S. public may be needed, and will update guidance as more information becomes available.

How long after completion of the initial vaccine series are you recommending the additional dose?

The additional dose of an mRNA COVID-19 vaccine can be administered any time, as long as it is at least 28 days after completing the initial two-dose mRNA COVID-19 vaccine series (such as for Pfizer and Moderna).

Talking with a health care provider may help you find the best time to get the vaccine so you get the most benefit from the vaccine and any immunosuppressive treatments.

If I am eligible for an additional dose, do I have to return to the same vaccination location where I got my first and second doses?

No, you can receive the additional dose wherever mRNA COVID-19 vaccines are offered. Try to make sure the vaccination location has the same kind of vaccine you received for your first two doses.

If possible, bring your white CDC COVID-19 vaccination card or a printed or downloaded summary of your immunization record.


Know the vaccine facts

Get information on available COVID-19 vaccines, vaccine effectiveness, and the vaccine development process.

Medical professional getting read to vaccinate an adult

Last Revised: August 18, 2021

211 Wisconsin

Call 211 or 877-947-2211 to get referrals for thousands of services across Wisconsin. For COVID-19 questions, text COVID to 211-211. Language assistance is available.

Resilient Wisconsin

Get help learning how to manage stress and adapt to change with services and support from organizations across the state.

Helpful resources

Find help with housing, income, food, employment, health care, mental health concerns, safety at home, and more—in multiple languages.