Virus Experts Are Making This Urgent Warning About Booster Timing

This important guidance comes just days ahead of Thanksgiving weekend.

After months of back and forth about the need for booster shots among various age groups, all adults in the U.S. are finally eligible for an additional dose thanks to authorization from the Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC). More than 36 million people in the U.S. have gotten their booster so far, according to data from the CDC. And now that millions more are eligible as of Nov. 19, appointments for booster shots are booking up for the upcoming weeks. But while getting an additional COVID vaccine dose can keep you safe during holiday gatherings, the timing of your booster does play a part in its protective power.

RELATED: Dr. Fauci Has an Urgent New Warning for Vaccinated People.

Ahead of the Thanksgiving holiday, virus experts are warning individuals going to get their booster shot now that they won't have added protection by the time they gather with friends and family.

"It does take time for your immune system to ramp up. So, with regards to people traveling for Thanksgiving, [a booster now is] going to have no impact," Ulysses Wu, MD, director of infection disease and chief epidemiologist for Hartford HealthCare's System, told the group's Health News Hub on Nov. 22.

As with the first two shots, your booster shot will need time to build up protection. "It takes at least seven days for the booster to really have effect," Peter Marks, MD, director of the Center for Biologics Evaluation and Research (CBER) for the FDA, told USA Today.

But reaching full protection from this shot might take even longer that that. Mo Kharbat, MBA, the vice president of pharmacy services for SSM Health of Wisconsin, told Channel 3000 in Madison, Wisconsin, that while your immune system will begin reacting and producing antibodies as soon as you get your booster shot, "it will take two weeks or so to build up enough antibodies to prevent a COVID infection."

This echoes the advice White House COVID adviser Anthony Fauci, MD, gave recently. Fauci told NPR that while your immunity begins to rebound within a few days after getting a booster shot—like Marks and Kharbat indicated—you won't actually get the peak of your protection from the shot for two to four weeks.

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Of course, this doesn't mean you shouldn't go ahead and get your booster as soon as possible. Lon Young, MD, the chief medical officer for CapRock Health System in Texas, told CBS-affiliate KBTX that even just a few days in between your booster and a COVID exposure could make a difference.

"If you got the booster even a few days before Thanksgiving and you were exposed, it takes several days before an infection would set in," Young explained. "During that time, the booster has some time to work, and so it would lessen the infection that you got. There's never really a bad time to get a booster. It's never too late to get a booster."

And if you get your booster now, you'll definitely have time to build up optimal protection before the December holidays. David Weber, MD, a professor of medicine for the University of North Carolina at Chapel Hill, told CBS-affiliate WNCN in Raleigh, North Carolina, that if you get a booster by Nov. 23, your antibodies would likely kick in by Dec. 6—putting you at peak protection for Christmas and New Year's.

"It's not like this an automatic line [like] you're not protected at day 13 and you're protected at day 14 really. It is the further out from the booster of the somewhat better protection you get," Weber explained. "If they want to go to religious ceremonies, fun things to do, like New Year's parties, or going out to restaurants and bars, then they ought to get their booster shot as soon as feasible."

RELATED: This Is How Long Your Booster Will Last, New Study Says.

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