Vaccination with ChAdOx1 nCoV-19 or BNT162b2 is estimated to be about 90 percent effective for preventing deaths from COVID-19 caused by the B.1.617.2 (delta) variant, according to a research letter published online Oct. 20 in the New England Journal of Medicine.
Aziz Sheikh, M.D., from the University of Edinburgh in the United Kingdom, and colleagues conducted a cohort study using a Scotland-wide surveillance platform to estimate vaccine effectiveness against death from delta variant infection among adults aged 18 years or older from April 1 to Aug. 16, 2021, who were followed to Sept. 27, 2021. The analysis of mortality was based on 114,706 adults who tested positive for severe acute respiratory syndrome coronavirus 2.
The researchers found that among individuals aged 16 to 39 years, there were no deaths among the fully vaccinated versus 17 among unvaccinated individuals. Vaccine effectiveness was 88 and 95 percent with ChAdOx1 nCoV-19 and BNT162b2, respectively, among those aged 40 to 59 years; vaccine effectiveness was 90 and 87 percent, respectively, for those aged 60 years or older. Vaccine effectiveness against death from the delta variant 14 days or more after the second vaccine dose was 91 and 90 percent for ChAdOx1 nCoV-19 and BNT162b2, respectively.
“With the delta variant now the dominant strain in many places worldwide and posing a higher risk of hospitalization than previous variants seen in the U.K., it is reassuring to see that vaccination offers such high protection from death very shortly after the second dose,” Sheikh said in a statement.
One author disclosed ties to AstraZeneca, the manufacturer of the ChAdOx1 nCoV-19 vaccine.