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Plus, know the difference between a booster shot and a third dose.

As more and more people are vaccinated against COVID, you may have some questions. Do you need a booster shot? How is a booster different from a third dose?

Find out exactly what you need to know to protect yourself from COVID-19.

What’s the difference between a third dose and a booster shot?

A third dose of the vaccine and a booster shot work in the same way — by providing added protection against a virus. However, there is a key difference between them.

A third dose is given to people who are moderately to severely immunocompromised and whose immune systems may not have built up enough protection with the first two doses of the vaccine.

On the other hand, a booster shot is given to people several months after their initial vaccine series, which may include a third dose for immunocompromised people, to “boost” and maintain their immunity over time.

“A third dose should be given to people no sooner than 28 days after their second dose of an mRNA vaccine, and it must be from the same series as doses one and two,” says Dr. Stanley Martin, infectious diseases specialist at Geisinger. 

But when should you get boosted? It depends on which vaccine you initially received and your age:

  • Pfizer: Age 12+ and 5 months after your second dose
    • Immunocompromised: Age 12+ and 5 months after your third dose
  • Moderna: Age 18+ and 5 months after your second dose
    • Immunocompromised: Age 18+ and 5 months after your third dose
  • Johnson & Johnson: Age 18+ and 2 months after your single dose

Who’s eligible for a third dose?

Anyone age 5+ who is moderately to severely immunocompromised and has had two doses of either the Pfizer or Moderna COVID vaccines should receive a third dose. An additional dose is not recommended for anyone who received the Johnson & Johnson vaccine.

You’re eligible for a third dose if you have received the Pfizer (age 5+) or Moderna (age 18+) COVID vaccine and 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 2 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 steroids or other drugs that may suppress the immune response

Whether you receive a third dose of Pfizer or Moderna, it’ll be the same dosage as you received previously.

Who’s eligible for a booster shot?

Booster shots are approved for anyone age 12+ who received their initial one- or two-shot series of the Moderna, Pfizer or Johnson & Johnson COVID vaccines.

“Moderately and severely immunocompromised people age 12 and older may also receive a booster shot, but only after receiving their third dose of a COVID vaccine,” says Dr. Martin.

How do I schedule my third dose or booster?

You can schedule your COVID-19 vaccine through MyGeisinger. Don’t have a MyGeisinger account? Call 570-284-3657. You can also check the PA DOH website or local pharmacies to see if a booster shot is available sooner elsewhere in your community.

If you received your first two vaccine doses at another location, you can come to Geisinger for your third dose or booster shot. Just bring your vaccine card to your Geisinger appointment.

“Another dose of a COVID vaccine can help protect you further against COVID-19 and its variants,” says Dr. Martin. “As we are starting to see the spread of the omicron variant in the U.S., it’s becoming increasingly clear that these boosters may make a big difference in protecting us from this variant.”

Next steps:

Learn about a third dose vs. a booster
What to know about breakthrough COVID infections
Schedule your COVID-19 vaccine or booster appointment