JUST TWO doses of Pfizer or AstraZeneca’s COVID-19 vaccine are nearly as effective at warding off the highly contagious Delta variant of the coronavirus as it was against the previously dominant Alpha variant. This is shown from a study published on Wednesday (7/21).
Officials say the vaccine is highly effective against the Delta variant, which is now the dominant variant worldwide, although the study reaffirms that a single shot of the vaccine is not sufficient for high protection.
The study, published in the New England Journal of Medicine, confirms key findings provided by Public Health England in May on the efficacy of COVID-19 vaccines made by Pfizer-BioNTech and Oxford-AstraZeneca.
Wednesday’s study found that two doses of Pfizer injections were 88% effective at preventing symptomatic disease of the Delta variant, compared with 93.7% of the Alpha variant, generally the same as previously reported.
Two injections of the AstraZeneca vaccine were 67% effective against the Delta variant, up from 60% originally reported, and 74.5% effective against the Alpha variant, compared with the initial estimate of 66% effectiveness.
“Only a small difference in vaccine effectiveness was noted with the Delta variant compared to the Alpha variant after receiving two doses of the vaccine,” the Public Health England researchers wrote in the study.
Data from Israel predicts a lower effectiveness of Pfizer injections against symptomatic disease, although protection against severe disease remains high. PHE previously said that the first dose of the two vaccines was about 33% effective against symptomatic disease of the Delta variant.
The full study published on Wednesday found that a single dose of Pfizer injection was 36% effective, and a single dose of AstraZeneca vaccine was about 30% effective.
“Our finding of decreased effectiveness after the first dose will support efforts to maximize uptake of the two-dose vaccine among susceptible groups in the context of circulating Delta variants,” the study authors said. [antaranews/photo special]