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Covid-19 Primary Care Resources


Covid variants and vaccine effectiveness



Why maximising vaccine uptake with 2 doses among vulnerable groups is crucial

This information is sourced from a Gov UK press release, a medRxiv preprint study, The Guardian the WHO and Nature:

Variants of Concern

The WHO have introduced a new naming scheme for Variants of Concern which aims to avoid confusion and stigmatisation:

WHO labelPango lineageEarliest documented samples
AlphaB.1.1.7UK, Sept 2020
BetaB.1.351South Africa, May 2020
GammaP.1Brazil, Nov 2020
DeltaB.1.617.2India, Oct 2020

UK Vaccine effectiveness

The health secretary has announced that up to three-quarters of new UK Covid cases are now thought to be caused by the variant first detected in India (Delta)

A PHE funded study looked at vaccine effectiveness of 1 or 2 doses of the Pfizer and AstraZeneca vaccines from the period from 5 April to 16 May 2021. The preprint publication shows that:

In those who had had 2 doses of a vaccine

  • the Pfizer vaccine was 88% effective against symptomatic disease from the Delta variant 2 weeks after the second dose, compared to 93% effectiveness against the Alpha variant
  • 2 doses of the AstraZeneca vaccine were 60% effective against symptomatic disease from the Delta variant compared to 66% effectiveness against the Alpha variant
  • Higher levels of effectiveness against hospitalisation and death are expected (not evidenced in the study)

In those who had had 1 dose of a vaccine

Both vaccines were 33% effective against symptomatic disease from Delta , 3 weeks after the first dose compared to around 50% effectiveness against the Alpha variant

Written by Dr Poppy Freeman