Find out if you need a COVID-19 vaccine booster

Last updated December 10, 2021.

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Many people who have already been fully vaccinated against COVID-19 should now receive a booster to stay protected. While vaccines work very well to prevent COVID-19, immunity can drop over time. Getting a booster dose when it’s time is the best way to keep up protection for you, your family, and your community.

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

Booster doses

Who should get a booster dose? 

You should get a booster dose if you:

  • Are 16 or older and received your second dose of Pfizer at least six months ago.

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

  • Are 18 or older and received the Johnson & Johnson vaccine at least two months ago.

Anyone age 16 or older who is due for a booster should make a plan to get one. We encourage you to speak with your health care provider if you have questions about boosters.

 

Does my booster 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 booster dose. Teens aged 16-17 may only receive the Pfizer vaccine for their booster at this time.

 

Why do I need a booster dose?
  • Booster doses make sure you stay protected from COVID-19. Vaccine effectiveness varies by vaccine product and may decrease over time. A booster dose can help raise immunity levels back up, keeping you from getting sick or needing to go to the hospital. 

  • Coloradans who are boosted:

    • 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 booster dose?

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

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

Additional doses for immunocompromised people

Who should get an additional dose?

You should get an additional 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 third dose should be the same vaccine product as the first two, but either mRNA vaccine is fine if you can’t get the same kind. If you are 12 to 17 years old, your additional dose must be Pfizer. Children younger than 12 are not recommended to receive additional doses at this time.

 

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

 

Why do I need an additional dose?
  • The additional 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 mRNA vaccines. 

 

Where can I get an additional dose?
  • You can get an additional 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.

Frequently asked questions

  • Additional doses are for people with weakened immune systems. Studies show that some people who are immunocompromised don’t build enough protection after receiving two doses of mRNA vaccines. The third dose completes the primary vaccination series and helps protect people with weakened immune systems. 

  • Booster doses are for people who did build enough protection after getting vaccinated at first, but whose protection may have decreased over time.

  • 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.

  • You may 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 six months since you got your third (additional) dose, you should get a booster dose, for a total of four doses.

  • Yes. Right now, the definition of “fully vaccinated” is still the same. 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.

  • 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 hundreds of thousands of Coloradans – doctors, nurses, seniors, and others – 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 full 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.