Two doses of the coronavirus vaccine developed by pharmaceutical company AstraZeneca has shown 60% efficacy against symptomatic infection caused due to the B.1.617.2 variant of the coronavirus that was first detected in India, the United Kingdom’s government health body Public Health England said on Sunday.

The vaccine was found to be 66% effective against the B.1.1.7 variant that was first detected in the UK, a study cited by the health body showed.

The Serum Institute of India is the local maker of the coronavirus vaccine – locally called Covishield – developed by Oxford University and pharmaceutical company AstraZeneca.

The study found that the Covid-19 vaccine collaboratively developed by pharmaceutical companies Pfizer and BioNTech was 88% effective against symptomatic cases of the B.1.617.2 variant (first detected in India), and 93% against the B.1.1.7 strain (first found in the UK).

The Public Health England on Sunday said that the difference in effectiveness between the vaccines after two doses may be attributed to the fact that the Oxford-AstraZeneca vaccine was rolled out after the Pfizer shot. The health body considered this as a factor as it said that other data on antibody profiles have shown that the AstraZeneca vaccine takes longer to reach maximum effectiveness.

The Public Health England added that the data indicated higher levels of effectiveness against hospitalisation and death.

“This study provides reassurance that two doses of either vaccine offer high levels of protection against symptomatic disease from the B.1.617.2 variant,” Mary Ramsay, Head of Immunisation at Public Health England said. “We expect the vaccines to be even more effective at preventing hospitalisation and death, so it is vital to get both doses to gain maximum protection against all existing and emerging variants.”

The study, however, mentioned the caveat that the number of cases and follow-up periods were currently insufficient to estimate effectiveness of the vaccines against severe disease, including hospitalisation and mortality.

The B.1.617.2 variant of the coronavirus contains two key mutations to the outer “spike” portion of the virus that attaches to human cells. The World Health Organization 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. “There is increased transmissibility demonstrated by some preliminary studies,” Maria Van Kerkhove, WHO’s technical lead on Covid, had said. The variant has already spread to other countries, and many nations have moved to cut or restrict travel to and from India.

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