While American doctor and epidemic expert Eric Feigl-Ding expressed reservations about the efficacy of Delta variant vaccines. He asserted that AstraZeneca's vaccine, known as Covishield in India, was only 60 per cent effective against the Delta variant.
Meanwhile, the Lancet discovered that vaccines are less effective against the Delta variant, especially when given in a single dose. The efficacy of Pfizer-vaccine BioNTech's drops from 92 per cent against the Alpha variant to 79 per cent against the Delta variant after two doses, according to the study.