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

New research has given insight into how long a booster will protect you from COVID.

The U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) have now authorized booster shots for all adults. CDC Director Rochelle Walensky, MD, said this new decision was the result of "compelling evidence" indicating that booster shots have safely increased people's protection against both symptomatic infection and severe COVID. Many health officials had been pushing for the agencies to make this decision over the past few weeks, as research has shown that protection from the vaccines has been waning over time in all age groups. But if the immune response from the first two shots fell after just a few months, how long will the added protection from a COVID booster last?

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It's too early to say for sure, but new research has revealed promising results. A Nov. 21 study from Northwestern University offers new insight into what the antibody response in a healthy adult looks like after receiving a COVID booster shot. The researchers analyzed more than 30 participants who were fully vaccinated five to nine months prior to getting a booster, finding that all recipients experienced a significant increase in their antibody response following an additional shot of Pfizer or Moderna.

According to the study, neutralizing antibody levels against COVID decreased about 10-fold nine months after participants had gotten both doses of either the Pfizer or Moderna vaccine. But after getting a booster, these levels climbed 25-fold. This is five-fold higher than what was seen after the second shot, leading researchers to conclude that protection may very well last longer after the booster shot than it did after the second dose.

"Because these antibody levels are so robust, the booster could potentially give us protection for a longer duration than what we saw for two doses of the vaccine," co-corresponding study author Alexis Demonbreun, PhD, assistant professor of pharmacology at the Northwestern University Feinberg School of Medicine, said in a statement.

She added, "We really do think the robust effect we are observing after booster vaccination in this small cohort will be mirrored in much larger populations."

According to the study, a booster for either mRNA vaccine generated such a significant antibody response that levels were higher than those produced by any other form of protection, including natural infection, two vaccine doses, or even both natural infection and vaccination.

"The findings are relevant to anyone who is vaccinated and considering a booster," co-corresponding author Thomas McDade, PhD, professor of anthropology in the Weinberg College of Arts and Sciences, said in a statement. "We know the mRNA vaccines provide a high level of protection against serious cases of COVID-19 that lead to hospitalization or death. But immunity wanes over time—particularly levels of antibodies that help prevent infection—and we are seeing higher rates of breakthrough infections as a result, particularly in combination with the rise of the more infectious Delta variant."

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The findings of this study coincide with recent comments from top White House COVID adviser Anthony Fauci, MD. During a Nov. 21 interview on ABC's This Week, Fauci said he is hopeful that a single COVID booster shot is strong enough to protect individuals long-term.

"We would hope—and this is something that we're looking at very carefully—that that third shot with the mRNA not only boosts you way up, but increases the durability so that you will not necessarily need it every six months or a year," Fauci said.

He added, "My hope as an immunologist, as an infectious disease person, that that maturation of the response increasing its strength and power will be followed by a greater durability … If it doesn't, and the data show we do need it more often, then we'll do it."

Even if its protection doesn't last forever, it's still important to go get a booster now. "There's no lack of clarity, that if you've been vaccinated with a primary vaccination, with an mRNA vaccine, either the Pfizer or the Moderna six months or more ago, get boosted and the same with regard to J&J, if you were vaccinated two months ago, get boosted," Fauci said.

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