Two doses of Pfizer or AstraZeneca coronavirus vaccineare highly effective against the Delta strain, which is now the dominant COVID-19 variant in the world. These vaccines have also proved to be effective against thepreviously known Alpha mutation.
This was evidenced by the results of a study conducted in the United Kingdom. The study wa published in the New England Journal of Medicine.
The analysis showed that effectiveness after one dose of both Pfizer and AstraZeneca vaccines (BNT162b2 or ChAdOx1 nCoV-19) was notably lower among persons with the delta variant (30.7%; 95% confidence interval [CI], 25.2 to 35.7) than among those with the alpha variant (48.7%; 95% CI, 45.5 to 51.7).
With Pfizer, the effectiveness of two doses was 93.7% (95% CI, 91.6 to 95.3) among persons with the alpha variant and 88.0% (95% CI, 85.3 to 90.1) among those with the Delta variant. With the AstraZeneca, the effectiveness of two doses was 74.5% (95% CI, 68.4 to 79.4) among persons with the alpha variant and 67.0% (95% CI, 61.3 to 71.8) among those with the delta variant.
Thus, the study indicated Pfizer and AstraZeneca effectiveness against the Delta variant.
“This finding would support efforts to maximize vaccine uptake with two doses among vulnerable populations,” the study concludes.