Two shots of Pfizer, AstraZeneca COVID-19 vaccines effective against Delta variant: study

COVID-19 vaccine
In a real-world study in the U.K., two doses of COVID-19 vaccines produced by Pfizer-BioNTech and AstraZeneca were shown to be effective at preventing severe cases which can be traced to the Delta variant of the disease, which emerged from India.(Kunal Mahto/iStock/Getty Images Plus/Getty Images)

As the coronavirus surged across the globe, experts have raised concerns that skyrocketing infections would cause mutations that evade current vaccines.

As more data comes in, those concerns are fading.

A real world study conducted by Public Health England shows that two doses of the vaccines produced by Pfizer-BioNTech and AstraZeneca are highly effective in preventing hospitalizations due to the troublesome Delta variant (B.1.617.2), which scientists first detected in India. The variant has become the predominant coronavirus strain in the U.K.

Of those who received two doses of the Pfizer-BioNTech vaccine, 96% avoided hospitalization with no deaths. Of those who received two shots of the AZ vaccine, 92% avoided hospitalization with no deaths.

The study included 14,019 people in England who had contracted the Delta variant of the virus. Of them, 166 were hospitalized from April 12 to June 4.

“It is absolutely vital to get both doses as soon as they are offered to you, to gain maximum protection against all existing and emerging variants,” Mary Ramsay, M.D., the PHE’s chief of immunization said in a statement.

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Interestingly, a single shot of the mRNA vaccine produced by Pfizer-BioNTech performed much better (94%) than a single shot of the AZ vaccine (71%) in preventing hospitalization.  

Pfizer CEO Albert Bourla said on CBS on Tuesday that once variants started emerging, his company responded by testing its vaccine against them.

“I feel quite comfortable that we cover it,” Bourla said of the threat from the Delta strain. “We will not need a special vaccine for it. The current vaccine should cover it.”  

Vaccine effectiveness against symptomatic disease was significantly lower. AZ’s shots, for example, provided 64% protection against symptoms from the Delta variant.

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But the company, hounded by safety concerns and supply problems with its vaccine, cited the report saying its shot will remain an important tool for combatting the virus.

“The data show that the vaccine will continue to have a significant impact around the world given that it continues to account for the overwhelming majority of supplies to India and the COVAX facility,” Mene Pangalos, AZ’s head of R&D, said in a statement.