Nov 22, 2021 10:30 AM

Author: University of Utah Health Communications

Información en español

A “booster shot” is not something unique to COVID-19. In fact, booster shots are common for many of the vaccines that doctors and health officials recommend for everyone. The most common booster shots people get are annual flu vaccines and boosters for Tdap (tetanus, diphtheria, and pertussis) every 10 years.

Similar to the rationale behind giving boosters for those illnesses, COVID-19 booster shots can help your body maintain a higher level of immunity and protection against breakthrough COVID-19 infections

Who Is Eligible for COVID-19 Booster Shots?

COVID-19 booster shots are authorized for anyone ages 12 and older. Eligible individuals may “mix and match” the vaccines, meaning they may choose any of the three COVID-19 vaccines authorized in the U.S. to receive as a booster dose.

A second booster dose of either the Pfizer-BioNTech or the Moderna COVID-19 vaccines are also available for some people. Individuals 50 years of age and older can receive a second booster dose at least four months after their first booster dose. Certain immunocompromised individuals can also receive their second booster dose at least four months after their first booster dose. "Emerging evidence suggests that a second booster dose of an mRNA COVID-19 vaccine improves protection against severe COVID-19 and is not associated with new safety concerns," according to the FDA.

The Rationale for COVID-19 Booster Doses

On September 25, 2021, the Centers for Disease Control and Prevention (CDC) issued the first set of guidelines on who may get a booster dose of COVID-19 vaccine. This came after public health officials looked at data from other countries where people got a booster dose several months after their primary vaccine series. 

  • The most extensive study on COVID-19 booster shots came from Israel, where the government administered a booster shot to almost all adults. Researchers evaluated 1.1 million people over the age of 60 who got a booster. After 12 days, those people were almost 20 times less likely to test positive for COVID-19 and have severe symptoms than people who did not get a booster shot.
  • Currently available data suggests that immunity against COVID-19 goes down over time, and a booster shot can help your body stay protected longer.

Q&A: COVID-19 Vaccine Booster Shots

What if I’m not in one of the recommended groups but I want a COVID-19 booster shot?

Anyone who is not in the recommended groups for booster shots should talk to their doctor to discuss options.

Is it safe to get a COVID-19 booster shot and a flu vaccine at the same time?

Both the flu vaccine and COVID-19 booster vaccines are approved by the FDA. There is no evidence that it is risky to get both shots together, so if you need a flu shot and a COVID-19 booster, you can get both at the same time.

How important is it to get a booster dose of the COVID-19 vaccine?

The CDC guidance says that everyone ages 12 year and older should get one. This is stronger than just a recommendation. It is especially true because of more transmissible and contagious strains of the virus. In addition, preliminary studies show that a booster provides better protection against Omicron.

If I’m experiencing long COVID symptoms, do I need a booster shot?

There is some evidence that the immune protection that develops after getting a COVID-19 infection may not last as long as immunity after full vaccination. Getting a booster shot, even if you are still experiencing “long-hauler” symptoms, can be helpful. You may want to consult with your doctor.

Is it true that someone treated with monoclonal antibodies shouldn’t get a booster?

Monoclonal antibody treatments are effective for people within the first 10 days of being infected with COVID-19. If you were treated with this therapy, you should wait at least 90 days before getting a COVID-19 booster shot. Otherwise, the treatment might interfere with the vaccine and keep it from doing its job to build up immunity in your body to future COVID-19 infections.

How can I get a booster shot?

The good news is that it’s very easy to get a booster shot. You can make an appointment at your local health department or find a pharmacy nearby that has doses available by visiting Many pharmacies also take walk-ins. Don’t forget to take your vaccine card with you.

You can find more information about COVID-19 booster shots and older adults from our physicians at U of U Health by watching a video of our Facebook Live broadcast.


This information was accurate at the time of publication. Due to the changing nature of the COVID-19 pandemic, some information may have changed since the original publication date.

covid-19 coronavirus covid-19 vaccine booster shots

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