COVID-19 Vaccines Proven Highly Effective Against Delta Variant: What You Need to Know

Real-Time Data on Vaccine Effectiveness Against SARS-CoV2 Variants

Introduction to the Delta Strain

As the SARS-CoV2 virus continues to evolve, researchers and healthcare professionals are actively gathering real-time data to assess the effectiveness of various vaccines against emerging strains, particularly concerning mortality rates linked to the virus. Among the recent strains of interest is the delta variant (B.1.617.2).

Cohort Study in Scotland

A cohort study was conducted in Scotland to evaluate the effectiveness of vaccines in preventing death caused by the delta variant of the SARS-CoV2 virus. This study analyzed data collected from April 1 to August 16, 2021, coinciding with the period when the Pfizer-BioNTech and AstraZeneca vaccines became accessible to all adults aged 18 and older.

Study Methodology

In the study, participants were categorized into ‘vaccinated’ and ‘unvaccinated’ groups. The vaccinated group was further subdivided based on the type of vaccine received and the number of doses (one dose, both doses but contracted the virus within two weeks of the second shot, or both doses with virus contraction occurring more than two weeks after the second shot).

The analysis included data from 1,563,818 individuals, of whom 114,706 tested positive for the virus during the study period. Among these cases, there were 201 recorded deaths.

Findings on Vaccine Effectiveness

The study revealed significant findings regarding mortality rates. In the younger age group (18 to 39 years), there were no deaths among those who were fully vaccinated. However, in the subsequent age bracket, a slight increase in the risk of death was observed among fully vaccinated individuals.

The results indicated that both the Pfizer-BioNTech and AstraZeneca vaccines provided substantial protection against death associated with the delta variant, irrespective of the individual’s age.

Reference

Sheikh A, Robertson C, Taylor B. BNT162b2 and ChAdOx1 nCoV-19 Vaccine Effectiveness against Death from the Delta Variant. N Engl J Med. 2021 Oct 20:NEJMc2113864. doi: 10.1056/NEJMc2113864. Epub ahead of print. PMID: 34670038; PMCID: PMC8552534.

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