Covid-19 vaccines made by AstraZeneca and the Pfizer-BioNTech alliance remain broadly effective against Delta and Kappa Covid-19 variants which were first identified in India, according to a scientific study, underpinning a continued push to deliver the shots.

The study by Oxford University researchers, published in the journal Cell, investigated the ability of antibodies in the blood from people, who were vaccinated with the two-shot regimens, to neutralise the highly contagious variants, a statement said.

"There is no evidence of...