Vaccine Efficacy Against Delta Variant: Preliminary Research Offers Insights

Strategic Insights -

Preliminary research on the Pfizer Inc-BioNTech SE and Oxford University-AstraZeneca PLC vaccines has revealed varying levels of effectiveness against new Covid-19 infections associated with the Delta variant. While two doses of the Pfizer vaccine initially provide greater protection, its efficacy declines faster compared to the AstraZeneca jab. The study, conducted in partnership with the Office of National Statistics and the Department for Health & Social Care, analyzed data from over 700,000 participants and found that protection from the Pfizer vaccine decreased from 90% to 78% over three months, whereas the AstraZeneca vaccine maintained its effectiveness throughout the duration. The research also suggests that those infected with the Delta variant after their second jab may have similar peak levels of virus to unvaccinated individuals, emphasizing the importance of vaccination.

Key Takeaways:

  • Two doses of the Pfizer vaccine provide greater effectiveness initially against new Covid-19 infections associated with the Delta variant, but its efficacy declines faster compared to the AstraZeneca vaccine.
  • After four to five months, the level of protection offered by both vaccines is similar, with the AstraZeneca jab maintaining its effectiveness throughout the duration.
  • Those infected with the Delta variant after their second jab may have similar peak levels of virus to unvaccinated individuals.
  • The study found that a single dose of the Moderna vaccine had similar or greater effectiveness against the Delta variant as single doses of the other vaccines.
  • The time between doses did not affect effectiveness in preventing new infections.
  • Younger people aged 18-34 had more protection from vaccination than older age groups.

Statistics:

  • Protection from the Pfizer vaccine decreased from 90% to 78% over three months.
  • The equivalent protection for AstraZeneca was 67%, 65%, and 61%.
  • A single dose of the Moderna vaccine had similar or greater effectiveness against the Delta variant.
  • The study analyzed data from over 700,000 participants.
  • 90% of the Pfizer vaccine's protection was lost after three months for infections with a high viral load.

Sources:

  • (Source: University of Oxford)
  • University of Oxford's Nuffield Department of Population Health
  • Office of National Statistics
  • Department for Health & Social Care
  • PA Copyright 2021 Alliance News Limited. All Rights Reserved.
  • Nilima Marshall, PA Science Reporter (Author)