Updated: Oct 7, 2022
A study published in the NEJM on July 21, 2021, revealed that the effectiveness of the AstraZeneca vaccine or the BioNtech/Pfiezer vaccine against the delta variant of the COVID-19 virus is 79.6% compared to 87.5% against the Alpha variant of fully immunized people after the second dose of the virus. Whereas, the effectiveness after the first dose did not exceed 31%.
The study raises concerns regarding the current recommendation of delaying the second dose of the AstraZenca vaccine till 12 weeks after the first dose. This will leave the partially vaccinated people more vulnerable and prone to contracting COVID-19!.
J. L. Bernal et al. , Effectiveness of Covid-19 Vaccines against the B.1.617.2 (Delta) Variant. July 21, 2021, DOI: 10.1056/NEJMoa2108891