Find out when you need a third (booster) dose of a COVID-19 vaccine

Last updated January 10, 2022.

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Many people who are already vaccinated against COVID-19 should now receive another dose for the highest level of protection. While vaccines work very well to prevent COVID-19, immunity can drop over time. Getting a third dose when it’s time is the best way to keep up protection for you, your loved ones, and the community.

COVID-19 vaccines are safe, effective, and free. You don’t need an ID or insurance to get a vaccine. Find a third dose near you.

Third (booster) doses

Who should get another dose? 

You should get another dose if you:

  • Are 12 or older and received your second dose of Pfizer at least five months ago.

  • Are 18 or older and received your second dose of Moderna at least five months ago.

If you got the Johnson & Johnson vaccine, you should get a dose of either Pfizer or Moderna two months or more after you first got vaccinated.

If you are immunocompromised and got three doses of Pfizer, you should get a fourth dose five months after your third. If you are immunocompromised and got three doses of Moderna, you should get a fourth dose five months after your third dose.

Anyone age 12 or older who is due for a third dose should make a plan to get one. We encourage you to speak with your health care provider if you have questions.

 

Does my third dose need to be the same kind of vaccine as my initial doses?
  • It depends on your age. If you’re 18 or older, you can get any authorized vaccine for your third dose. We strongly recommend getting either Pfizer or Moderna. People aged 12-17 may only receive the Pfizer vaccine for their third dose at this time.

 

Why do I need another dose if I am already fully vaccinated?
  • Three doses of a COVID-19 vaccine give you the highest level of protection from severe illness, hospitalization, and death. Vaccine effectiveness varies by vaccine product and may drop over time. A third dose (or second if you got J&J) helps make sure you stay protected after a certain amount of time has passed since you first got vaccinated. This can keep you from getting sick or needing to go to the hospital.

  • Coloradans who got three doses:

    • Are 2.4 times less likely to get infected with COVID-19 than people who only received two doses of Pfizer or Moderna or one dose of Johnson & Johnson. 

    • Are 9.7 times less likely to get infected with COVID-19 than people who haven’t been vaccinated at all. 

    • Are 3.3 times less likely to be hospitalized with COVID-19 than people who only received two doses of Pfizer or Moderna or one dose of Johnson & Johnson. 

    • Are 47.5 times less likely to be hospitalized with COVID-19 than people who haven’t been vaccinated at all.

 

Is it safe to get a third dose?

Yes. Recent data from CDC shows third doses are safe. The side effects of a third dose are about the same as the side effects of the primary vaccine doses.

 
Where can I get a third dose?
  • You can get a third dose at any vaccine provider. No ID, insurance, or proof of medical history is required. Third doses are free.

Additional primary doses for immunocompromised people

Who should get an additional primary dose?

You should get an additional primary dose of Pfizer or Moderna if:

  • You have a moderately to severely weakened immune system and received either Pfizer or Moderna vaccines for your first two doses. Your additional primary dose should be the same vaccine product as the first two doses, but either mRNA (Pfizer or Moderna) vaccine is fine if you can’t get the same kind. If you are 12 to 17 years old, your additional primary dose must be Pfizer. Children 5 through 11 years of age who have undergone solid organ transplantation, or who have been diagnosed with conditions that are considered to have an equivalent level of immunocompromise, are authorized to receive a third primary dose of Pfizer vaccine to receive the maximum potential benefit from vaccination.

 

I am immunocompromised and received the Johnson & Johnson vaccine for my first dose. Can I get an additional primary dose?
  • At this time, an additional primary dose for immunocompromised people who received Johnson & Johnson has not been authorized. However, if it has been two months or more since you first got vaccinated, you can get a second (booster) dose of a COVID-19 vaccine. We recommend receiving either Pfizer or Moderna for this second dose, but you may get Johnson & Johnson if you can’t or would prefer not to get Pfizer or Moderna.

  • People who received Johnson & Johnson for their first dose are not recommended to get more than two total vaccine doses at this time.

 

When should I get an additional primary dose?
  • You should receive an additional primary dose at least 28 days after your second dose of Pfizer or Moderna vaccine.

 

Why do I need an additional primary dose?
  • The additional primary dose makes sure you have enough protection against COVID-19. Studies show that some people who have a weakened immune system don’t build enough protection after receiving two doses of Pfizer or Moderna vaccine. 

 

Where can I get an additional primary dose?
  • You can get an additional primary dose at any vaccine provider. No ID, insurance, or proof of medical history is required. Additional doses are free. You may self-report having a high risk condition to vaccine providers, but doing so is not required.

Frequently asked questions

  • This includes but is not limited to 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 or other drugs that may suppress your immune response.

  • Talk with a health care provider about your medical condition and whether getting an additional dose makes sense for you, but it’s not required to have a conversation with your provider before getting an additional dose.

  • Coloradans looking to get an additional dose may self-attest that they are eligible. You do not need to provide your medical history to receive an additional dose.

  • Yes. If it has been at least five months since you got your additional primary dose of Pfizer vaccine or Moderna vaccine, you should get a dose for a total of four doses.

  • Right now, the CDC's definition of “fully vaccinated” is still the same. If an event or venue is checking your vaccination status, you are considered fully vaccinated if more than two weeks have passed since your second dose of Pfizer or Moderna, or your single dose of J&J vaccine.

  • We strongly recommend getting three doses of the vaccine (or two doses if you first got J&J) for the highest level of protection.

  • No. You do not need to be a full-time resident of Colorado, or of a particular Colorado county, to be vaccinated.

  • Vaccines must be proven to be safe and effective before they are given to people. The COVID-19 vaccines are no different. These vaccines are being proven safe every day, as millions of Coloradans have already taken them. Nationwide, many millions of people have also received the vaccine.

  • The FDA requires that vaccines undergo a rigorous scientific process, including three phases of clinical trials, before they authorize or approve the vaccine. The COVID-19 vaccines are subject to the same safety standards as other vaccine trials.

  • You may experience mild to moderate side effects after receiving the vaccine. Side effects are about the same for the first, second, and third doses of the vaccines. Side effects typically go away on their own after a few days. The most commonly reported side effects are: 

    • Pain, swelling, and redness at the injection site.

    • Pain, tenderness, and swelling of the lymph nodes in the same arm of the injection.

    • Fatigue.

    • Headache.

    • Muscle pain.

    • Chills.

    • Joint pain.

    • Nausea/vomiting.

    • Fever.

  • Different people may experience different side effects, even if they receive the same vaccine. 

  • The process of building immunity can cause symptoms. These symptoms are normal and show that your body’s immune system is responding to a vaccine. Other routine vaccines, like the flu vaccine, have similar side effects.

  • If you experience discomfort after the first dose of the Pfizer or Moderna vaccine, it is very important that you still receive the second dose a few weeks later for the highest level of protection.

  • For in-depth information about the side effects of the vaccines, see the CDC’s report on Pfizer vaccine, Moderna vaccine, and Janssen (Johnson & Johnson) vaccine. 

For more information on the COVID-19 vaccine, please call:

1-877-CO VAX CO (1-877-268-2926)
Available Monday through Friday, 8 a.m. to 8 p.m.;
Saturday and Sunday, 9 a.m. to 6 p.m. MT.
Answers available in multiple languages.

The call center will be closed on Nov. 25, Dec. 25, and Jan. 1 for the holidays.