Are Booster Shots Common for Vaccines?

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

The Food and Drug Administration (FDA) has since authorized a booster dose for all three COVID-19 vaccines available in the U.S.

On November 19, the FDA amended its emergency use authorization (EUA) for both the Pfizer and Moderna COVID-19 vaccines, approving the use of a single booster dose for all persons 18 years and older who completed the primary series. The FDA later authorized a Pfizer booster shot for adolescents ages 12 to 17 and children 5 to 11 who completed their initial Pfizer vaccination series.

The agency had previously authorized a booster for all adults who received one shot of the Johnson & Johnson vaccine and for specific groups of people at increased risk for COVID-19 exposure or severe illness.

Eligible adults are able to choose any authorized COVID-19 booster. However, it is now recommended that individuals get the Pfizer or Moderna mRNA COVID-19 vaccine over the Johnson & Johnson vaccine, following concerns about blood-clotting side effects. The Johnson & Johnson shot still remains an option for those who are not able or willing to get a different vaccine.

Children and adolescents ages 5 to 17 who completed Pfizer's primary series are only eligible for the Pfizer booster.

The Pfizer and Johnson & Johnson boosters will be administered with the same dosage as the initial vaccine, whereas Moderna’s will be a half dose (50 micrograms).

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. Other live vaccines may require two doses, like the measles, mumps, and rubella (MMR) and chickenpox vaccines. 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 two, four, and six months; boosters at 12 to15 months.
• Haemophilus influenzae type b (Hib): two doses by four months; boosters at 12 to 15 months
• Polio: three doses by 18 months; boosters at four to six years—depending on which vaccine is used.

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 new variants.

“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.”

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.