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Why Oxford AstraZeneca's Coronavirus Vaccine Data Has Come Under Scrutiny
Oxford University and AstraZeneca have acknowledged a manufacturing error meant some trial participants received only a partial dose of their experimental COVID-19 vaccine.
The announcement has raised questions about why researchers did not mention the error when they claimed the jab was “highly effective” just days ago.
It has also raised some concerns about the part of the study which showed a 90% success rate. Oxford and AstraZeneca have since addressed these issues and explained the next steps for the jab, to ensure its safety and effectiveness.
Here is what we know:
The study
On Monday, Oxford and AstraZeneca announced preliminary results from trials showed an average efficacy of 70% – a figure reached by pooling the results from two different dosing regimens.
One month apart, one set of volunteers received two identical doses while the other received a half-dose, and then a full dose. In the first group, the efficacy was 62%. In the second, 90%.
The results were hailed a success, but it has since been revealed that some volunteers were only given a half dose because some of the vials did not have the right concentration of vaccine.
Mene Pangalos, R&D lead at AstraZeneca, admitted to this dosing error to Reuters on Monday.
The manufacturing error was only caught when some of the people in the study did not show the usual adverse effects. Oxford has said it discussed the problem with regulators and completed the late-stage trial with two groups.
The second subgroup — the one that had a 90% efficacy — was also limited to participants aged 55 and below.
In a statement on Wednesday, Oxford acknowledged a difference in manufacturing and measurement processes meant later phases of its clinical studies resulted in half a dose being administered instead of a full one.
“The methods for measuring the concentration are now established and we can ensure that all batches of vaccine are now equivalent,” it said.
What this could mean
Some...
