If You Get the Pfizer Booster, This Is How Protected You Are From Delta

This is the latest data for recipients of all three COVID vaccines.

In late September, Pfizer boosters were authorized for adults 65 and older and those 18 to 64 with underlying medical conditions or high-risk exposure to COVID by the U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC). These select groups initially had to be six months out from having received their second Pfizer dose, but on Oct. 20, the FDA officially authorized mixing and matching vaccine boosters. So now, eligible Moderna and Johnson & Johnson recipients are also able to get a Pfizer booster before official recommendations come out from the CDC about the Moderna and Johnson & Johnson boosters. Wondering if you should get a Pfizer shot now? New research now shows how much a Pfizer booster protects you from Delta.

RELATED: Dr. Fauci Says You Need a Booster ASAP If You Got This Vaccine.

On Oct. 21, Pfizer and BioTech released new results from their Phase 3 controlled trial, which evaluated the efficacy and safety of a 30-microgram booster dose of the Pfizer vaccine in more than 10,000 individuals 16 years and older. According to the trial, the Pfizer booster increased relative vaccine efficacy to 95.6 percent when compared to those who did not receive a booster during a period in which Delta was the dominant strain in the U.S. This "restored vaccine protection against COVID-19 to the high levels achieved after the second dose," the researchers noted.

In the study period, there were only five cases of breakthrough COVID in the boosted group, while there were 109 cases in the non-boosted group. "Multiple subgroup analyses showed efficacy was consistent irrespective of age, sex, race, ethnicity, or comorbid conditions," the researchers said in the study, adding that there were no additional safety concerns identified with the booster compared to other doses.

"These results provide further evidence of the benefits of boosters as we aim to keep people well-protected against this disease," Albert Bourla, PhD, the chairman and chief executive officer of Pfizer, said in a statement.

Ugur Sahin, MD, the chief executive officer and co-founder of BioNTech, added, "These important data add to the body of evidence suggesting that a booster dose of our vaccine can help protect a broad population of people from this virus and its variants. Based on these findings we believe that, in addition to broad global access to vaccines for everyone, booster vaccinations could play an important role in sustaining pandemic containment and a return to normalcy."

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The Pfizer study was only conducted in those who had initially received this vaccine as a two-dose series. But the National Institutes of Health (NIH) and the National Institute of Allergy and Infectious Diseases (NIAID) recently released a study evaluating and comparing the efficacy and safety of the three boosters to different initial vaccine series among nearly 500 participants. According to this study, a Pfizer booster also raised protection levels among recipients of the other two vaccines.

The researchers found that for Johnson & Johnson recipients, the Pfizer booster raised neutralizing antibodies 35-fold after 15 days. And for those who initially received Moderna, the additional Pfizer shot boosted levels more than 11-fold. For those who got Johnson & Johnson, the impact of Pfizer's booster was significantly stronger than just getting another dose of Johnson & Johnson. But for Moderna, the increase of an additional dose of Pfizer was not as notable compared to getting a Moderna booster.

In fact, a Moderna booster increased neutralizing antibodies more for original Pfizer recipients. In these individuals, Moderna's third dose boosted antibodies more than 31-fold, while Pfizer's additional dose boosted them 20-fold, according to the NIH study.

As for which booster you should get, the FDA did not tout the effectiveness of one over another. "We do not have preferential recommendations," Janet Woodcock, MD, the FDA's acting commissioner, said at a news briefing, per The New York Times. "We feel that if patients have questions, they should consult with perhaps their physician or another provider."

RELATED: If You Got This COVID Vaccine, Get a Different Booster, New Study Says.

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