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Pfizer's COVID-19 booster shot strongly extends protection but CDC cautions 3rd dose not yet needed

USA TODAY logo USA TODAY 7/9/2021 Karen Weintraub, USA TODAY
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A booster shot of the COVID-19 vaccine made by Pfizer and BioNTech strongly extends protection, a new study from the companies shows, and they are developing a vaccine targeted directly at the Delta variant, which first arose in India.

The companies say they have demonstrated that a third dose of their vaccine, given six months after the second, increases neutralizing antibodies five to tenfold against the original virus and the so-called Beta variant, which was first identified in South Africa. The booster was also found to be safe.

A healthcare worker prepares a dose of the Pfizer/BioNTech Covid-19 vaccine at the Oman Convention & Exhibition Centre in the capital Muscat on June 23, 2021 during the second phase of the national immunisation plan against coronavirus. (Photo by Haitham AL-SHUKAIRI / AFP) (Photo by HAITHAM AL-SHUKAIRI/AFP via Getty Images) ORG XMIT: 0 ORIG FILE ID: AFP_9CX7WV.jpg © HAITHAM AL-SHUKAIRI, AFP via Getty Images A healthcare worker prepares a dose of the Pfizer/BioNTech Covid-19 vaccine at the Oman Convention & Exhibition Centre in the capital Muscat on June 23, 2021 during the second phase of the national immunisation plan against coronavirus. (Photo by Haitham AL-SHUKAIRI / AFP) (Photo by HAITHAM AL-SHUKAIRI/AFP via Getty Images) ORG XMIT: 0 ORIG FILE ID: AFP_9CX7WV.jpg

They plan soon to publish this data and submit it to the Food and Drug Administration for authorization.

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Neither the companies nor the government recommend booster shots yet, until their safety and effectiveness can be fully explored.

In a joint statement late Thursday, the FDA and the Centers for Disease Control and Prevention emphasized that people who have been fully vaccinated do not need booster shots yet. 

"FDA, CDC, and NIH are engaged in a science-based, rigorous process to consider whether or when a booster might be necessary," according to the government statement. "This process takes into account laboratory data, clinical trial data, and cohort data – which can include data from specific pharmaceutical companies, but does not rely on those data exclusively … We are prepared for booster doses if and when the science demonstrates that they are needed."

The highly contagious Delta variant now accounts for just over half the COVID-19 cases in the United States, according to the CDC.


Video: Pfizer believes Covid booster shot may offer better protection (NBC News)

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A Pfizer-BioNTech news release issued Thursday afternoon said that because two doses of their vaccine appears to be effective against the Delta variant, the companies believe a third dose would extend that protection.

"Pfizer and BioNTech are conducting tests to confirm this expectation," according to the release.

Protection against severe disease remained strong six months after vaccination, but effectiveness against symptomatic disease began to decline toward the end of that period, the companies said. That, plus the arrival of new variants, "are key factors driving our belief that a booster dose will likely be necessary to maintain highest levels of protection," the new release concluded.

The companies are also updating their vaccine, called BNT162b2, to directly address the Delta variant. They are currently producing material for a clinical trial, which they expect to begin in August, pending regulatory approvals.

Olivier Schwartz, head of the Virus and Immunity Unit, at Institut Pasteur in Paris, published a scientific article Thursday, showing that two doses of the Pfizer-BioNTech vaccine protects against the Delta variant, though a single dose does not.

"The vaccines are good," he said, likely including Moderna's and the single-dose Johnson & Johnson vaccine, which was also recently shown to be effective against the Delta variant. But it's not clear how long that protection will last. 

Neutralizing antibodies needed to fight the virus decline substantially by one year after a natural infection, he said. Someone who was infected and then receives a single shot increases their antibody levels 100- to 1,000-fold, he said. "If you have already been infected during the first wave, receiving one dose of vaccine is very efficient," he said.

The Delta variant has rendered ineffective a treatment made by Lilly, known as a monoclonal antibody cocktail, Schwartz' study showed. The Food and Drug Administration recently removed authorization for that treatment, although a similar one, made by Regeneron, remains available and effective, he said. 

Contact Karen Weintraub at kweintraub@usatoday.com.

Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.

This article originally appeared on USA TODAY: Pfizer's COVID-19 booster shot strongly extends protection but CDC cautions 3rd dose not yet needed

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