Your Guide To COVID-19 Boosters: Who Needs Them, When—And Why

The Food & Drug Administration (FDA) recently authorized COVID-19 Pfizer booster shots for children ages 5 and up. And last month, the FDA authorized a second booster shot for all adults ages 50 and older. Adults 18 and older who are moderately to severely immunocompromised are also eligible for a second booster.

While some wonder whether booster shots are necessary, Dennis Cunningham, M.D., medical director of infection control and prevention at Henry Ford Health, says they are.  

“The COVID-19 vaccines aren’t the only vaccines that require a few doses to ensure their effectiveness,” says Dr. Cunningham. “Let’s take the tetanus shot, for example. You need several doses before you’re really protected, and then after the first series of shots, a shot every 10 years to maintain your protection. It’s similar with the COVID-19 vaccines: they do work, but their effectiveness decreases over time, which is why boosters are important. Protection from boosters last about four to six months.”

The vaccines are also effective against COVID-19 variants, including the Omicron subvariants, and even if you do contract COVID-19, they will reduce the likelihood that you’ll experience a severe illness. But we know that boosters can be confusing—who should get one and when? Here’s what to know.

When To Get Your First Booster Shot

In order to get boosted, you need to complete your primary vaccine series. Here’s what that means:

• If you’ve had two doses of Pfizer, and you are not immunocompromised, you have completed your primary vaccine series. If you are immunocompromised, you need a third dose of Pfizer to complete your primary series.
• If you’ve had two doses of Moderna, and you are not immunocompromised, you have completed your primary vaccine series. If you are immunocompromised, you need a third dose of Moderna to complete your primary series.
• If you’ve had one dose of Johnson & Johnson, you have completed your primary series.

Getting your first booster if you’ve completed your primary series with Pfizer

Ages 5 and older who completed their primary vaccine series with Pfizer at least five months ago can receive one booster shot. Ages 5 to 17 can receive only a Pfizer booster shot. Ages 18 and up can receive a booster shot of Pfizer, Moderna or Johnson & Johnson, although the CDC says Pfizer and Moderna boosters are preferred in most situations. (Unless you are allergic to ingredients in the Pfizer or Moderna vaccines, for example.)

Getting your first booster if you’ve completed your primary series with Moderna

Ages 18 and older who completed their primary vaccine series with Moderna at least five months ago can receive one booster shot of Pfizer, Moderna or Johnson & Johnson, although the CDC says Pfizer and Moderna boosters are preferred in most situations. (Unless you are allergic to ingredients in the Pfizer or Moderna vaccines, for example.)

Getting your first booster if you’ve completed your primary series with Johnson & Johnson

Ages 18 and older who completed their primary series at least two months ago with Johnson & Johnson can receive one booster shot of Pfizer, Moderna or Johnson & Johnson, although the CDC says Pfizer and Moderna boosters are preferred in most situations. (Unless you are allergic to ingredients in the Pfizer or Moderna vaccines, for example.)

When To Get Your Second Booster Shot

While all adults might eventually be able to receive a second booster shot, those who are most vulnerable to COVID-19 are currently eligible for a second booster. 

“We know that older individuals, and those who are immunocompromised, are at a higher risk of contracting a severe case of COVID-19,” says Dr. Cunningham. “These booster guidelines reflect that and aim to protect our most at-risk population.”

• If you are over the age of 50 and you received your first booster shot at least four months ago, you are eligible to receive another booster of Pfizer or Moderna.
• If you are 18+ and you are immunocompromised (meaning you have undergone a solid organ transplant, or you are living with a condition that is considered to be equally immunocompromising) and you received your first booster dose at least four months ago, you are eligible to receive another booster of Pfizer or Moderna.
• If you are 18+, you completed your primary vaccine series with Johnson & Johnson, and you received a Johnson & Johnson booster shot at least four months ago, you can receive a second booster dose of a Pfizer or Moderna vaccine.

But What If You’re Young And Healthy?

Maybe you understand the need for older adults or those with certain health conditions to keep up with their booster shots. But if you’re young and healthy, you might not feel compelled to get boosted. Dr. Cunningham still thinks you should.

“While younger, healthy people are at a lower risk for a severe case of COVID-19, that doesn’t mean it can’t happen,” says Dr. Cunningham. “There have been children and young adults in the hospital with COVID-19. You don’t want to wait to get sick to know whether your case will be severe. Also, those who have asymptomatic cases of COVID-19 can experience long-haul symptoms like brain fog and fatigue. And getting boosted doesn’t just protect you, but it helps to keep everyone around you protected from COVID-19.”

Henry Ford offers COVID-19 vaccines and boosters to established patients. Appointments can be scheduled in MyChart. Boosters for patients ages 5 to 17 will be available in the coming weeks. For updates on booster guidelines and availability of vaccines by age group, visit henryford.com/coronavirus/vaccine-faqs.  

Dr. Dennis Cunningham is the medical director of infection control and prevention at Henry Ford Health.