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Are Booster Shots Common for Vaccines?

Older man looking at his arm where he was vaccinated.

Jasmin Merdan / Getty Images

Key Takeaways

  • Starting September 20, at-risk adults will likely be eligible for a COVID-19 booster shot if they received their second dose at least eight months ago.
  • Experts say boosters for vaccines are relatively common and sometimes necessary for bolstering protection against a virus or disease.
  • You've likely received a booster shot before—for example, adults should receive tetanus shots every ten years.


President Joe Biden announced on Wednesday, August 18, that booster shots would become available in mid-September for certain adults who have been fully vaccinated against COVID-19.

While COVID-19 is a new virus, the idea of booster shots isn’t. Verywell spoke to experts about the use of booster shots for other routine vaccines you may be familiar with.

Booster Shots Are Common

According to Jason C. Gallagher, PharmD, FCCP, FIDP, FIDSA, BCPS, clinical professor at Temple University’s School of Pharmacy and clinical specialist in infectious diseases, boosters are common.

“Most vaccines that are given in the U.S. require several doses to render immunity,” Gallagher tells Verywell. “I like to think of [a COVID-19 vaccine booster] as the third dose of a multi-dose series.”

While boosters are common, whether they’re necessary largely depends on the type of vaccine, Jeffrey Langland, PhD, virologist, and professor at Southwest College of Naturopathic Medicine, tells Verywell.

“Most vaccines that do not contain a live, attenuated (weakened) virus, typically require multiple doses or boosters,” Langland says.

One dose of some live vaccines can offer you a lifetime of protection against disease, like shots for smallpox and chickenpox. Other live vaccines may require two doses, like the measles, mumps, and rubella (MMR) vaccine. Children typically get their first dose at 12–15 months old and their second (and final) dose between age 4–6.

But other types, like inactivated vaccines, will need several doses over time to remain effective. Boosters are currently recommended for several vaccines—chances are you’ve likely received one in your lifetime.

For example, adults should receive a tetanus vaccine—a recommended series of childhood and adult immunizations to protect against lockjaw—every ten years. You’re recommended to get others, like the flu shot, annually.

“We give the influenza vaccine annually since the virus constantly evolves, and we work to catch up with strains that dominate,” Gallagher says.

You start receiving boosters at an early age, Langland notes. These childhood vaccinations include:

  • Pneumococcal: three doses at 2, 4, and 6 months; boosters at 12–15 months and 65 years old
  • Haemophilus influenzae type b (Hib): two doses by 4 months; boosters at 12–15 months
  • Polio: three doses by 18 months; boosters at 4–6 years

Although most of these vaccines offer strong protection against diseases, the immunity offered by the shots often wanes over time. That’s where boosters come in.

Additional doses help amplify the body’s immune response. “A second or even third dose is given to boost the immune response, and it is this response that really primes the immune system to tackle the disease when it is encountered,” Gallagher says. 

Because both the COVID-19 virus and vaccines are new, Langland says scientists are still learning about the duration of protection offered by the shots. But some data suggests the vaccines may now be offering reduced protection against mild and moderate disease with the rise of the Delta variant.

Pfizer’s early data suggests that a COVID-19 booster can bolster protection. Participants aged 18 to 55 who received a booster developed antibodies that targeted the Delta variant five-fold.

“We are still learning how long either natural immune memory lasts after a natural infection and how long it lasts after the vaccine,” Langland says. “The boosters help the immune system learn about the virus better and better each time a booster is received.”

What This Means For You

Booster doses are currently authorized for immunocompromised people. But extra doses for the general public will likely become available in the fall. If you are immunocompromised, reach out to your physician or contact 1-800-232-0233 to find out where to get the booster shot. Booster shots are given free of charge.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

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Article Sources
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  1. U.S. Department of Health and Human Services. Vaccine types. Updated April 29, 2021.

  2. Centers for Disease Control and Prevention. Measles, mumps, and rubella (MMR) vaccination: what everyone should know. Updated January 26, 2021.

  3. Centers for Disease Control and Prevention. COVID-19 booster shot. Updated August 20, 2021. 

  4. Pfizer. Second quarter 2021 earnings teleconference. Published July 28, 2021.