Researchers from the University of Oxford have today released their findings about the so-called ‘correlates of protection’ against symptomatic COVID-19; potentially a tool to speed up safe development of new vaccines which may assist regulators in assessing the likely potency of any new COVID-19 vaccine without the need for Phase III efficacy trial data.
Using an analysis based on COVID-19 cases detected in the United Kingdom, and immune system data from the blood samples of volunteers who took part in the UK trials of the Oxford vaccine, the researchers compare antibody levels in vaccine recipients 28 days after their second dose, and COVID-19 cases that occurred more than 7 days after the blood sample was taken.
Writing on MedRxiv, they report that higher levels of anti-spike, anti-RBD IgG, and neutralising antibody titres were associated with a greater degree of protection against COVID-19 – defined as a PCR positive test with at least one symptom present.
These data were then used to build a model to extrapolate the levels of antibody associated with varying degrees of protection, providing estimates for a range of vaccine efficacies from 50% to 90%, using three different assays. Standard values are also provided to bridge between assays from different laboratories.
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medRxiv. Preprint Research Paper:
