WHEATON, Ill. (CBS) — For many Illinoisans, getting COVID-19 vaccine shots didn’t mean much.

They are the immunocompromised, whose bodies do not build antibodies like an average person’s would. But as CBS 2’s Marie Saavedra reported Thursday night, a third chance at getting protected has arrived – with authorization from the Food and Drug Administration having came down late Thursday.

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“I’m certain I wouldn’t be here today if I didn’t have that transplant 26 years ago,” said Brent Flynn.

Tuesday marked the anniversary of when Flynn’s life changed for the better.

“In 1995, I received a kidney from my brother,” Flynn said, “then started the process of recovery from that and went back to living life as normal, for the most part.”

“Normal” means protecting his health at all costs. But it’s not always possible. Take his COVID vaccinations.

“Because of the compromised immune system that I have, my body may not react to that vaccine and give me 100 percent protection,” Flynn said.

But he will soon have another chance. U.S. regulators on Thursday said transplant recipients and others with severely weakened immune systems can get an extra dose of the Pfizer or Moderna COVID-19 vaccines.

“For all of us who need the booster, this is a big deal,” Flynn said.

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It is also a big deal for Dr. John Fung, co-director of University of Chicago medicine’s transplant institute.

“We’re seeing a reduction anywhere from 50 to 66 percent less responses than we see in the general population,” he said.

Fung’s patients can’t mount much or any of a defense against COVID, but third shots are helping. A Journal of the American Medical Association study published in the last two weeks found after a 3rd dose of Moderna, 49 percent of its kidney transplant patients saw a boost in antibodies.

“Fortunately it seems from the preliminary data that the third dose doesn’t give you worse symptoms than the second dose,” Fung said.

This recommendation goes beyond transplant patients to those who are being treated for specific types of cancer and anyone who is taking medications that suppresses their immune system. The Centers for Disease Control and Prevention estimates that’s about 3 percent of the adult population – which still equates to millions of Americans.

“My decision has been to wait until it’s been approved by the FDA,” Flynn said.

But once that happens Flynn and many others will be eager to get it. He doesn’t know how his body will react, but he’s hoping the third shot’s the charm.

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“It will give me a little bit of peace of mind that I’ve got an extra layer of protection – but how strong that is, we don’t know,” Flynn said.

Marie Saavedra