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Coronavirus (COVID-19): What Are Booster Shots?

Article Translations: (Spanish)

I’ve heard that it’s important to get a booster shot of the COVID-19 vaccine to be as protected as possible from the virus. Do kids need a booster shot too?

Yes, booster shots are recommended for everyone age 5 and older.

To understand why, it helps to know what a booster shot is. This is a dose of vaccine given after a person has had the original vaccine (sometimes called a primary dose or, if more than one dose, primary series). Immunity from the original vaccine can fade over time, and a booster shot can help the immune system “boost” the protection it provides.

Boosters aren’t new. They are given for many vaccines that kids and adults get. For example, kids get vaccines around the time they start school to boost the vaccines they got as infants and toddlers. Pregnant women get a Tdap booster to protect their newborn from pertussis. And anyone over 6 months old should get a flu shot each year, which is also a type of booster.

Why Do People Need a COVID-19 Booster Shot?

Safe and effective COVID-19 vaccines are recommended for all adults and children ages 6 months and up. They are very good at preventing serious illness, hospitalization, and death due to COVID-19.

As with other vaccines, the immune protection from the COVID-19 vaccine can fade over time. A booster shot is recommended for everyone age 5 and older when 5 months have passed since their primary series. And a second booster dose is available for some groups of people, including adults 50 years and older, and adolescents who have weak immune systems.

Is a COVID-19 Booster Shot the Same as an "Additional Dose"?

No. An additional dose is an extra dose of vaccine given as part of the primary series when a person is first vaccinated. Some people with weak immune systems might get a poor response from the primary series of the COVID-19 vaccine. This can include people who are being treated for cancer, have had an organ transplant, or take medicines that weaken the immune system. This added dose helps their immune system reach the same level of protection as in people with stronger immune systems.

Kids ages 6 months through 4 years with a weak immune system may need an additional dose if their immune system is weak. This depends on which vaccine they receive:

  • Kids who get the Pfizer-BioNtech vaccine get 3 doses in their primary series. This is true for both healthy kids as well as those with weak immune systems. No additional doses are needed for this group.
  • Kids who get the Moderna vaccine get 2 doses in their primary series. Kids with weak immune systems get an additional dose at least 4 weeks later.

Booster shots are not recommended for this age group.

Kids ages 5 and older receive 2 doses in their primary series. Those with weak immune systems get an additional dose at least 4 weeks later. They will still need a booster shot as time passes, just like everyone else. But they get their booster 3 months after their primary series instead of 5 months.

Teens 12 and up with weak immune systems also can get a second booster dose, 4 months after their first booster. So, kids ages 5–11 with weak immune systems will get a total of 4 shots, and those 12 and up will get a total of 5 shots.

What Does It Mean for My Family?

Being up to date on COVID-19 vaccination might mean a different number of doses for kids in different health situations. But it’s an important way to protect kids and adults from getting very sick. Talk to your doctor if you aren’t sure if your child needs an additional dose after their primary COVID-19 vaccine series, or to see when your child might need a booster shot.

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Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.

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