Does having a high COVID-19 antibody level mean you don't need a booster?

LOS ANGELES (KABC) -- U.S. regulators issued new guidance this week shortening the time that people who received Moderna or Pfizer's COVID-19 vaccine have to wait for a booster, and it's different than the Johnson & Johnson vaccine.

The Food and Drug Administration's decision Friday means Moderna recipients are eligible for a booster after at least five months have passed since their last shot. The Centers for Disease Control and Prevention agreed.

That's in line with new recommendations for recipients of the Pfizer vaccine. Initial Pfizer vaccinations are open to anyone 5 or older. But only Pfizer recipients 12 and older are eligible for boosters, and earlier this week, U.S. health authorities said they can get one five months after their last shot.

A booster after receiving the single-dose Johnson & Johnson vaccine already is urged two months later. However, those changing recommendations can be confusing and some people have resorted to trying to figure out things on their own.

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Omicron continues to break previous daily highs for case rates in California due to its transmissibility.

Los Angeles-area resident Tina Connell spoke with Eyewitness News this week and said it's time for her to get her booster, but before she does, she said she wants to check her antibody levels.

"I'm here to get an antibody test to see where my levels are," she said. "I feel like if my antibodies are high enough then I don't need to get the booster."

This is a tool many people are hoping will give them reassurance. An antibody test determines if your immune system is still making antibodies against coronavirus.

USC Verdugo Hills Pharmacist Elizabeth Khatchaturian said 95% of the people she's tested have waning antibodies at six months, but not everyone.

"There has been that 5%," she said.

So can people with higher antibody levels wait to get their booster shot?

"That's something we still don't know," said Kaiser Permanente Infectious Disease Specialist Dr. David Bronstein. "Even after all this time, there's no way of saying this specific antibody level is going to protect you against infection at this specific rate. We just don't know that because there's so much more than antibodies that we think about."

T cells, which play an essential part of the immune system, also protect against infection.

Bronstein said we can't measure T cells, but we can measure real world evidence that gives scientists a strong indication of when vaccine effectiveness starts to wane.

"When you do start seeing more and more breakthrough infections, even if they're just mild infections, that tells you that your level of immunity is going down," he said.

Bronstein said when less virus is circulating, antibody testing may have a place. But he said at this point in the pandemic, get the booster shot when it's indicated for you.

"Unless you're living in a cave somewhere, you will be exposed, and if you don't have that immune response ready to fight it off, bad things can happen," he said.

The antibody test, which cost Connell $25, showed her antibody levels are low, so she said she'll be getting her booster shot soon.

The Associated Press contributed to this report.