Double dose of AstraZeneca, Pfizer vaccines effective against Delta variant, says study
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A new study has found that two shots of Oxford AstraZeneca and the Pfizer vaccines are almost as effective against the Delta variant as they are against the Alpha variant. The Alpha variant of COVID-19 had dominated global infections before the more virulent Delta strain came along.
The study, published on Wednesday, in the New England Journal of Medicine, is also a confirmation for the findings in a real-world data study by Public Health England in May on the effectiveness of Pfizer-BioNTech and Oxford-AstraZeneca vaccines.
Nevertheless, the study also confirms that one dose of either of the vaccines won’t suffice in terms of strong protection needed against COVID-19 infections.
As per the findings, the Oxford AstraZeneca vaccine shows 67 percent efficacy against the Delta variant compared to 74.5% efficacy against Alpha. As for the Pfizer vaccine, the efficacy against Delta variant was found to be 88 percent while it had a reported efficacy of 93.7 percent against the Alpha COVID-19 variant.
The researchers state, “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.”
The study comes after Israel recently reported lower efficacy against symptomatic COVID-19 infections for the Pfizer vaccine while protection against severe illness remained strong.
For single shots of Pfizer and AstraZeneca, the study noted 36 percent and 30 percent effectiveness, respectively.
As per the study’s author, “Our finding of reduced effectiveness after the first dose would support efforts to maximize vaccine uptake with two doses among vulnerable groups in the context of circulation of the Delta variant.”
A version of the Oxford AstraZeneca vaccine is being administered in India as Covishield.