Pfizer data suggests 3rd dose of vaccine 'strongly' boosts protection against delta variant

Pfizer on Wednesday shared data about a third dose of its COVID-19 vaccine that suggests it "strongly" boosts protection against the more contagious delta variant of the coronavirus, which has driven a recent surge in U.S. cases and hospitalizations. 

The company also expects to have data from its ongoing study of the vaccine in younger children by the end of September. 

The drugmaker released the limited information from its ongoing booster trial as part of its second-quarter earnings report. The initial data indicated that a third shot of its original two-dose vaccine — developed in partnership with BioNTech —produced neutralizing antibody titers against the delta variant that are more than five times higher in younger people and more than 11 times higher in older people than after two doses.

Pfizer said it expects to publish more definitive data about a booster dose of its vaccine in the coming weeks, which will be shared as part of the ongoing discussions with the U.S. Food and Drug Administration and other global regulatory authorities.

The company has said it plans to ask the FDA for emergency authorization of a third dose as early as August. In its earnings presentation, Pfizer said it also expects to begin clinical studies of a delta variant vaccine to begin in August. 

Pfizer said it anticipates full FDA approval for its original two-dose COVID-19 vaccine by January 2022.

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FILE - A health worker administers a shot of the Pfizer-BioNTech COVID-19 vaccine to a man at UNRWA's al-Sheikh Redwan clinic in Gaza City, on July 27, 2021. (Photo by Majdi Fathi/NurPhoto via Getty Images)

Meanwhile, Pfizer-BioNTech is studying its vaccine in healthy children between the ages of 6 months to 11. It expects to have data on the shot’s safety and how well it protects children ages five to 11 by the end of September.

"The full dataset from this study, which will be required to support licensure in this age group, is expected by the end of 2021. Similar data packages will be submitted shortly thereafter to support (emergency use authorization) and licensure in children 6 months to 5 years of age," Pfizer said. 

Currently, the Pfizer-BioNTech COVID-19 vaccine has been cleared for those 12 and older. More than 191 million doses of the Pfizer shot have been administered in the U.S.

The delta variant has fueled a surge of infections across the country, largely among the unvaccinated, with the nation now averaging more than 57,000 cases a day and 24,000 COVID-19 hospitalizations. Previous studies have shown that two doses of Pfizer’s vaccine remain highly effective against symptomatic disease from the delta variant.

But as a result of the uptick in cases, the Centers for Disease Control and Prevention on Tuesday recommended even vaccinated people return to wearing masks indoors in areas where the variant is prevalent. CDC Director Dr. Rochelle Walensky cited new information about the ability of the delta variant to spread by those who have been fully vaccinated.

"Unlike the alpha variant we had back in May, where we didn't believe that if you were vaccinated you could transmit further, this is different now with the delta variant," she explained. "We’re seeing that now, infection is possible if you are a rare breakthrough infection that you can transmit further, which is the reason for the change."

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Walensky reiterated several times Tuesday that the "vast majority" of transmission happening in the country right now is occurring among unvaccinated individuals. 

Additionally, people who weren't vaccinated make up nearly all hospitalizations and deaths from COVID-19.

This story was reported from Cincinnati.