Which COVID Booster Shot Should You Receive Based on Your First Dose? Chicago's Top Doc Weighs In

Now that COVID booster shots from Pfizer and Moderna could soon be distributed, which one should you get?

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Editor's Note: Earlier this month, the Center for Disease Control and Prevention cleared the way for all adults to get a COVID-19 booster shot, if they want one. But now, with the emergence of the new Omicron variant, the CDC is intensifying that message — saying those over 18 years old should get one. Our original story continues below.

As millions of Americans become eligible to receive COVID-19 booster shots, how do you choose which vaccine is best for your additional dose?

Chicago's Commissioner of the Department of Public Health, Dr. Allison Arwady, broke down Thursday the best options based on your first dose.

The FDA opened the way for anyone eligible for a booster to get any of the country's three authorized brands for their extra dose. The FDA stressed the practicality of being able to get whatever booster a particular pharmacy or clinic is offering, particularly in nursing homes and other institutional settings where residents have received different shots over time.

Advisors with the Centers for Disease Control and Prevention also endorsed “mixing and matching” brands for the extra dose -- a key step in the federal push to broaden booster access for the U.S. public.

But neither agency gave recommendations surrounding combinations of vaccines and booster doses.

So here's what Arwady has to say:

If you got Johnson & Johnson for your first dose:

For those who received the Johnson & Johnson vaccine, Arwady said "we definitely are seeing people choosing to get the Pfizer or Moderna as their follow up dose," a move she "fully supports."

"If you got Johnson and Johnson, I have been advising folks if they got J&J, depending on the reason they chose J&J the first time, if they're going to get that booster I've been recommending getting likely one of the mRNA series - the Moderna or the Pfizer," she's said. "That's where we saw the biggest increase in antibodies in the studies."

Arwady noted that those who receive an additional Johnson & Johnson vaccine two months after getting the initial dose should get a third dose -- this time, choosing the from the other two available.

"I encourage anybody who got J&J two months after getting that one J&J dose, you should get another dose of vaccine," Arwady said. "If it doesn't matter to you which kind you get, I would recommend getting either Pfizer or Moderna."

She has noted, however, that "getting that second dose of J&J also majorly increases the protection."

If you got Moderna or Pfizer for your first dose:

Federal regulators have recommended getting the same shot as your first dose for booster doses, and Arwady said that applies particularly to those who got an mRNA vaccine.

"If you got Moderna or Pfizer, I would recommend sticking with the same one that you got initially," she said.

Doses of the two vaccine makers' booster shots are different, Arwady noted. Moderna's booster dose will be half of its original dosing, while Pfizer's booster shot is the same as the initial doses.

The reason why Moderna is a half dose is because Moderna had a higher dose of the mRNA the only active part of the vaccine to start with. So it's part of why the side effects are sometimes a little higher and the folks who have Moderna.

Still unsure which brand you should to get?

The decision to allow "mixing and matching" for booster doses comes after a highly anticipated study found the approach to be safe and effective, though the Moderna and Pfizer-BioNTech vaccines were found to spark a stronger immune system response than Johnson & Johnson.

The National Institutes of Health study, which was released earlier this month and has yet to be peer reviewed, found that people who received the Johnson & Johnson vaccine produced stronger antibody levels after receiving a booster shot made by Moderna or Pfizer, compared to a booster from Johnson & Johnson. Those who were originally vaccinated with the Pfizer or Moderna vaccines and received either company's booster shot produced comparably strong immune responses, the researchers observed.

For a complete breakdown of who is eligible for a COVID vaccine booster shot, click here.

NBC Chicago/Associated Press
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