Confused about which COVID booster to get? This guide will help.

Your booster shot doesn’t have to be the same vaccine as your first shot. Johnson & Johnson users should get Moderna or Pfizer.
Activity program coordinator Beatriz Alcantara holds a frightened Ellen Spiegel as pharmacy tech Kimberly Singletary administers her COVID-19 booster vaccination at Belmont Village Senior Living Fort Lauderdale on Oct. 27.
Activity program coordinator Beatriz Alcantara holds a frightened Ellen Spiegel as pharmacy tech Kimberly Singletary administers her COVID-19 booster vaccination at Belmont Village Senior Living Fort Lauderdale on Oct. 27. [ AMY BETH BENNETT | South Florida ]
Published Nov. 8, 2021|Updated Dec. 10, 2021

UPDATE: U.S. health officials updated their recommendations and now encourage all U.S. adults who got the Pfizer or Moderna vaccines to get a booster. Those who got the Johnson & Johnson vaccine should do so after two months. Ages 16 and 18 should get Pfizer booster shots six months after their last dose.

Time for another dose?

U.S. health officials have expanded who is eligible to get the COVID-19 booster shot. It’s now recommended that everyone ages 16 and up should get a booster six months after receiving the two-shot Pfizer or Moderna vaccine.

But adults who got the one-shot Johnson & Johnson vaccine should get a different booster shot two months after the initial dose.

Confused? You are not alone.

As science’s understanding of COVID-19 evolves, so have the tools and advice developed to protect against the virus. But that can create confusion for patients, said Dr. Paul Nanda, a family doctor at Tampa General Hospital.

“(Patients) are seeing the evolution of the scientific method in progress,” Nanda said.

Related: Experts explain why kids ages 5 to 11 should get the COVID vaccine

As researchers continue to develop new and better methods to protect the community, Nanda said, the best thing people can do to clear up any confusion is to rely on their doctors and public health experts for the best and latest COVID-19 guidelines.

Here are the latest guidelines on who should get a booster shot, when and which one.

Why are booster shots needed?

The effectiveness of vaccines wanes over time, said Dr. Nishant Anand, BayCare’s chief medical officer.

Getting a booster shot once you’re eligible, Anand said, will strengthen your immunity against the virus and help protect you from future strains.

Who can get boosters and when?

Immunity from the Pfizer-BioNTech or Moderna COVID-19 vaccine starts to wane six months after the initial dose.

That’s why the Centers for Disease Control and Prevention now recommends that everyone age 16 and above who received that vaccine should get a booster shot six months later.

At first, U.S. health officials only recommended it for older ages groups and risky occupations. But now they recommend that every U.S. adult get a booster.

The CDC and the FDA on Dec. 10 issued new recommendations encouraging 16- and 17-year-olds to get Pfizer booster shots six months after their last vaccine dose.

It’s the first time boosters have been recommended for minors. Experts don’t yet know if immunity will wane in vaccinated children ages 5-11, or if those ages will also need a booster in the future.

What if I got the Johnson & Johnson shot?

The one-shot Johnson & Johnson vaccine becomes less effective over time compared to the Pfizer or Moderna vaccine.

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The CDC recommends that anyone who received this vaccine should get a booster two months after the initial dose.

Related: How Florida seniors can stay safe from COVID

Are there side effects to the booster shot?

Depends on the individual, Anand said. Side effects can range from low-grade fever, minor arm pain, headache and fatigue to no symptoms at all.

In a study of 306 participants, the CDC found that side effects from a Pfizer booster shot largely mirror the experience of receiving the second dose of the Pfizer vaccine.

While vaccine side effects are uncomfortable and inconvenient, Anand said, they’re not necessarily a bad thing.

“Symptoms are a way to know your body is building an immune response to coronavirus,” he said.

Are boosters available for all three vaccines authorized in the U.S.?


What’s the best booster for the Pfizer vaccine?

You can get the same vaccine as your initial dose, or mix and match — getting a different booster from your original vaccine — which the CDC approved in October.

If you received the Pfizer vaccine, you would receive a similarly strong response with the Pfizer or Moderna vaccine, according to a recent National Institutes of Health study.

What’s the best booster for the Moderna vaccine?

The Moderna vaccine is also best followed by the Pfizer or Moderna booster, the study states.

What’s the best booster for the Johnson & Johnson vaccine?

The Johnson & Johnson shot is ideally followed by either mRNA vaccine, Pfizer or Moderna, according to the study.

Related: Got questions about vaccinating your kid? Here are some answers.

Can I mix and match vaccines? Does it matter which booster I get?

The CDC’s latest recommendations allow for mixing vaccines.

What’s most important is that getting the booster — any of the three — is enough to strengthen your immunity and offer protection from future strains, Anand said. They are all safe and effective boosters.

“The most important thing is to go out and get the booster,” Anand said.

I underwent a three-dose vaccine regimen. Do I need a booster?

If you are moderately to severely immunocompromised and have already received three doses of the vaccine, you may get a booster shot at least six months after your additional dose, the CDC says. That’s four total doses.

Immunocompromised people who have questions about an additional dose or the booster should consult their doctor to discuss their specific health situation.

Are booster shots and dosages different from the original vaccines?

The formulas of the boosters are the same as the original vaccines. In the case of Moderna, the booster is half the dose of the shot people received in their initial series, according to the CDC.

The dosage remains the same for Pfizer and J&J.

Do I need a booster to be considered fully vaccinated?

Anyone two weeks after receiving both shots of the Pfizer or Moderna vaccine or one J&J shot continues to be considered fully vaccinated, the CDC says.

I got vaccinated, then got COVID. Do I still need a booster?

Preliminary data suggest that vaccinated people who recovered from COVID-19 gain additional protection, or “super immunity,” Anand said.

But the doctor recommends that individuals who are immunocompromised or older than 65 should still get the booster to ensure the strongest immune response against COVID-19 as possible.

Does the booster protect against the delta variant? What about future variants?

The booster shot protects people from the delta variant. And the more people in a community are vaccinated, Anand said, the less likely a new variant emerges and becomes resistant to the vaccine.

Will I need another booster in the future?

It’s possible, Anand said.

The pandemic is still ongoing, and the virus could continue to spread. Experts expect the coronavirus to evolve into an endemic, where the virus remains present in society but disease spread is controlled.

Malaria, for example, is endemic in some areas of Africa and South America. Seasonal influenza, or the flu, is also endemic. Just as we get the flu vaccine every year, Anand said, we will likely need an annual COVID-19 shot to protect us from the virus.

“This is something we’ll learn to live with,” the doctor said, “as our body learns to fight it off and it won’t make it as sick.”

Related: Get a flu shot and the COVID vaccine to help Florida avoid a ‘twindemic’

Can I get my flu shot and my first vaccine shot — or booster — at the same time?

Yes. Contracting one virus could weaken the immune system and render someone vulnerable to the other one. So get both vaccines to protect yourself from both viruses, and get them at the same time if that’s convenient.

Now that children ages 5 to 11 are eligible to get vaccinated, they too can get both their COVID-19 and flu shots.

I’m still hesitant about getting the COVID-19 vaccine. Is it safe?

Yes. Among the more than a billion COVID-19 vaccines that have been administered around the world, Nanda said, there have been “very, very, very few” cases involving serious complications from the vaccine. The greater threat is COVID-19 itself: More than 753,000 people have died from the virus in the U.S. alone. In Florida, deaths now exceed 60,000.

Nanda said he got the Pfizer vaccine and the booster shot as soon as he was eligible. The family doctor works in a high-risk setting treating COVID-19 patients, but said his health is a testament to the effectiveness of vaccines and masks.

“I screen, treat or see COVID every day, all day, for 18 months, and I still haven’t gotten COVID,” he said.

Editor’s note: This story was updated Dec. 10 with the latest guidance from U.S. health authorities.

How can I get vaccinated?

The COVID-19 vaccines for ages 5 and up are being administered at doctors’ offices, clinics, pharmacies, grocery stores and public vaccination sites. Many allow appointments to be booked online. Here’s how to find a site near you:

Find a site: Visit to find vaccination sites in your zip code.

More help: Call the National COVID-19 Vaccination Assistance Hotline.

Phone: 800-232-0233. Help is available in English, Spanish and other languages.

TTY: 888-720-7489

Disability Information and Access Line: Call 888-677-1199 or email

• • •

Tampa Bay Times coronavirus coverage

KIDS AND VACCINES: Got questions about vaccinating your kid? Here are some answers.

PROTECTING SENIORS: Here’s how seniors can stay safe from the virus.

THE FLU AND COVID: Get a flu shot and the COVID vaccine to avoid a ‘twindemic.’

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