Two shots of Covid-19 vaccines are “highly effective” in preventing hospitalisation in cases of the Delta variant, the United Kingdom’s health body Public Health England said on Monday.

“The analysis suggests...the Pfizer-BioNTech vaccine is 96% effective against hospitalisation after two doses,” a statement read. “The Oxford-AstraZeneca vaccine is 92% effective against hospitalisation after two doses.”

The Public Health England said that work has been underway to “establish the level of protection against mortality from the Delta variant”.

“The analysis included 14,019 cases of the Delta variant – 166 of whom were hospitalised – between April 12 and June 4, looking at emergency hospital admissions in England,” the statement said.

In May, the United Kingdom’s health body found that two doses of the Oxford-AstraZeneca and the BioNTech-Pfizer vaccines offered 81% protection against the B.1.617.2 variant, while a single dose offered only 33%.

The Public Health England had in May said that the AstraZeneca vaccine was 89% effective after two doses and 53% after the first shot. To understand the protection provided by the vaccine better, the effectiveness was also compared four to 13 days after vaccination. In this, the AstraZeneca shot provided 58% effectiveness after the first shot and 90% after the second.

A similar study of the Pfizer-BioNTech vaccine showed that it was 90% effective against symptomatic disease after two doses, and 54% after the first shot. When studied four to 13 days after the first vaccine dose, the effectiveness rose to 57%, and it rose to 91% after the second dose.

However, the Public Health England had in May cautioned that this data was still developing and inconclusive.

The B.1.617 variant contains two key mutations to the outer “spike” portion of the virus that attaches to human cells, according to Reuters. The World Health Organization has said the predominant lineage of B.1.617 was first identified in India last December, although an earlier version was spotted in October 2020.

On May 10, the WHO classified it as a “variant of concern,” which also includes mutations first detected in Britain, Brazil and South Africa.

India, which launched its vaccination drive on January 16, has been inoculating its population with two Covid-19 vaccines. One is Serum Institute’s Covishield, developed in collaboration with the Oxford University and drug company AstraZeneca. The other is Covaxin, created in partnership of Indian drug company Bharat Biotech and the Union government’s Indian Council of Medical Research.

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