The CDC published new information Friday about the performance of COVID-19 booster shots.

In a new study, researchers found that after receiving a third dose of the vaccine, protection wanes over time.

When the omicron variant was dominant, effectiveness decreased as soon as four months after the third dose.

However, protection from serious illness was still high after the third dose.

In the study, effectiveness was higher among people who had received the booster shot, than among people who only received two doses of the vaccine.

Researchers also noted that effectiveness after a booster was higher when delta was the dominant strain.

Health experts expect protection from the vaccines to wane.

Previous evidence had already suggested that vaccines offered less protection against the omicron variant in comparison to earlier versions of the virus.

The CDC still recommends people to remain up to date with COVID-19 vaccinations to protect themselves against the virus.

The Centers for Disease Control and Prevention recommends the third COVID-19 shot to improve people's response to the vaccine.

But Dan Whithorn, 63, is back to square one.

"You pin your hopes on it, you hope but when you've had two that didn't work," Whithorn said.

Whithorn received his third dose of the COVID-19 vaccine in August.

After getting the shot, he said, "Lord, I hope it works."

It didn't work. After the two-shot vaccine and the third dose, Whithorn still has zero antibodies.

"I don't want to be sick," he said. "I don't want to go back in the hospital."

In 2019, a very active Whithorn, who was a runner, thought he was healthy, until a weakened heart stopped him in his tracks and put him on the transplant list.

In May 2020, he got a second chance with a new heart.

However, those 30 anti-rejection meds he takes every day to keep the new heart beating block the effects of the vaccine.

Contracting COVID-19, would break his heart, literally.

"I only get one heart and I've been told that many times by ICU nurses and all the transplant people who look over me," he said.

Whithorn spends a lot of time with his dog, stays close to family, masks up and avoids crowded places.

"Those people need to continue to be very careful. It's also incumbent on the rest of us who are immunologically intact to help to have a protective bubble around them by ourselves getting vaccinated," said Dr. Mark Rupp, chief of the University of Nebraska Medical Center infectious disease division.

Whithorn isn't giving up. He still has the hope that helped him through his darkest moments. He said he's much stronger now than he was 18 months ago. If approved, he'd go back for a fourth shot.

"It ties right into why get a COVID shot in the first place? Because it could work," he said.

"I don't have fear like some people have on what could happen because of a shot," Whithorn said. "What is more fearful would be as is if I got COVID with a new heart."

Watch the full story in the video above.

Related video above: The Psychology Behind Vaccine Hesitancy

Do I need a booster if I got the Johnson & Johnson vaccine?

Probably at some point, but health officials still are collecting the data needed to decide.

With boosters being planned in the U.S. as early as the fall for those who got the two-shot Pfizer and Moderna vaccines, recipients of the single-dose J&J jab might be wondering just how well their protection is holding up.

All the vaccines used in the U.S. — including the J&J vaccine — still are doing their job of preventing hospitalizations and deaths from COVID-19.

"I don't think there's any signal that the J&J vaccine is failing at its primary task," said Dr. Amesh Adalja, an infectious disease specialist at the Johns Hopkins Bloomberg School of Public Health.

Despite continued protection against severe disease, U.S. officials are planning to offer Pfizer and Moderna boosters eight months after the second shot based on evidence that effectiveness against infection wanes over time. Adding to the decision, the vaccines don't appear quite as strong against the highly contagious delta variant as they were against earlier versions of the virus.

U.S. Surgeon General Vivek Murthy said boosters "will likely be needed" for the J&J vaccine. Authorities expect more data to decide in the coming weeks.

That's in part because the J&J rollout didn't start until March, several months after Pfizer and Moderna vaccinations began. The J&J shot is made differently. And there's more data about how the Pfizer and Moderna vaccines fare against delta because they're more widely used in countries where the variant struck before its U.S. surge.

There is some real-world data showing J&J's shot holds up against the delta variant. A huge study of health workers in South Africa showed the vaccine remains highly effective against hospitalizations and death from the variant. And the vast majority of so-called "breakthrough" infections in vaccinated people were mild.

J&J has also presented lab data on virus-fighting antibodies that indicates its vaccine protects against the delta variant for eight months and counting. Another small lab study has raised questions about whether a two-dose approach would work better, an option J&J is studying.

A separate issue is whether people with severely weakened immune systems should get extra shots as part of their original vaccinations, since they don't respond as well to any vaccines. The government now recommends a third shot of the Pfizer or Moderna vaccines for organ transplant recipients and others in this group. But it's still collecting data before making a similar recommendation for another dose of the J&J vaccine.