COVID-19 Boosters: Who Needs Them, When—And Why?

All adults aged 50 and up are now eligible for a second COVID-19 booster shot, a recommendation authorized by the Food and Drug Administration (FDA) and recommended by the Centers for Disease Control and Prevention (CDC) (CDC). Adults aged 18 and up who are immunocompromised are also eligible for a second booster.

While some question whether another booster shot is required, Dennis Cunningham, M.D., medical director of infection control and prevention at Henry Ford Health believes it is.

"The COVID-19 vaccines aren't the only ones that need a few doses to be effective," says Dr. Cunningham. "Take, for example, the tetanus shot. You need several doses before you're truly protected, and then a shot every ten years after that to maintain your protection. It's similar to the COVID-19 vaccines: they work, but their efficacy diminishes over time, which is why boosters are necessary. Booster protection lasts about four to six months."

The vaccines are also effective against COVID-19 variants, including the new BA.2 variant, and even if you do contract COVID-19, they will reduce your chances of becoming seriously ill. But we understand that boosters can be perplexing—who should get one and when? Here's what you need to know.

When Should You Get Your First Booster Shot?

To get boosted, you must finish your primary vaccine series. This is what it means:

.You have completed your primary vaccine series if you have received two doses of Pfizer and are not immunocompromised. If you are immunocompromised, you will require a third Pfizer dose to complete your primary series.

.You have completed your primary vaccine series if you have received two doses of Moderna and are not immunocompromised. If you have a compromised immune system, you will require a third dose of Moderna to complete your primary series.

.You've finished your primary series if you've had one dose of Johnson & Johnson.

If you've finished your primary series with Pfizer, you can get your first booster.

Anyone over the age of 12 who completed their primary vaccine series with Pfizer at least five months ago is eligible for one booster shot. Only a Pfizer booster shot is available to children aged 12 to 17. Ages 18 and up can receive a booster shot of Pfizer, Moderna, or Johnson & Johnson, though the CDC recommends Pfizer and Moderna boosters in most cases. (Unless you are allergic to any of the ingredients in Pfizer or Moderna vaccines.)

If you've finished your primary series with Moderna, you'll be able to get your first booster.

Ages 18 and up who completed their primary vaccine series with Moderna at least five months ago are eligible for one booster shot of Pfizer, Moderna, or Johnson & Johnson, though the CDC recommends Pfizer and Moderna boosters in most cases. (Unless you are allergic to any of the ingredients in Pfizer or Moderna vaccines.)

If you've finished your primary series with Johnson & Johnson, you'll be able to get your first booster.

Ages 18 and up who finished their primary series with Johnson & Johnson at least two months ago can receive one booster shot of Pfizer, Moderna, or Johnson & Johnson, though the CDC recommends Pfizer and Moderna boosters in most cases. (Unless you are allergic to any of the ingredients in Pfizer or Moderna vaccines.)

When Should You Get Your Second Booster Shot?

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

"We know that older people and those with compromised immune systems are at a higher risk of contracting a severe case of COVID-19," says Dr. Cunningham. "These booster guidelines reflect that, with the goal of protecting our most vulnerable population."

.If you are over the age of 50 and received your first booster shot at least four months ago, you are eligible for another Pfizer or Moderna booster shot.

.If you are 18 or older, immunocompromised (meaning you have had a solid organ transplant or are living with a condition that is similarly immunocompromising), and you received your first booster dose at least four months ago, you are eligible for another Pfizer or Moderna booster.

.If you are 18 or older, finished your primary vaccine series with Johnson & Johnson, and received a Johnson & Johnson booster shot at least four months ago, you are eligible for a second booster dose of a Pfizer or Moderna vaccine.

But what if you're young and in good health?

Perhaps you understand the importance of booster shots for older adults or those with certain health conditions. However, if you are young and in good health, you may not feel compelled to get boosted. Dr. Cunningham believes you should.

"While younger, healthier people are less likely to develop a severe case of COVID-19, that doesn't mean it can't happen," says Dr. Cunningham. "There have been COVID-19 patients in the hospital." You don't want to wait until you get sick to find out if your case will be severe. Asymptomatic COVID-19 patients may also experience long-term symptoms such as brain fog and fatigue. And getting boosted not only protects you, but it also helps to keep everyone around you safe from COVID-19."