Delta variant, compared to 93.7% against the Alpha variant, broadly the same as previously reported. Two shots of AstraZeneca vaccine were 67% effective against the Delta variant, up from 60% originally reported, and 74.5% effective against the Alpha variant, compared to an original estimate of 66% effectiveness. "Only modest differences in vaccine effectiveness were noted with the Delta variant as compared with the Alpha variant after the receipt of two vaccine doses," Public Health England researchers wrote in the study.
Data from Israel has estimated lower effectiveness of Pfizer's shot against symptomatic disease, although protection against severe disease remains high.