After announcing that their coronavirus vaccine candidate was nearly 70% effective, the University of Oxford and its partner, AstraZeneca, on Wednesday admitted to a manufacturing error, which has now sparked important questions about the results.
Experts have said the pharma giant’s conduct has eroded confidence, though the company maintained that the trials “were conducted to the highest standards.”
Lower doses turned out to be more effective
The error concerns vaccine dosage received by some volunteers — AstraZeneca failed to explain why some participants didn’t get the desired doses.
When the results of the large-scale trial were out, it was learned that in cases of smaller doses, the vaccine was 90% effective. In larger doses, the efficacy was reduced to 62%.
Thereafter, the developers said the vaccine was approximately 70% effective.
Why did lower dose generate a better response?
The most important questions were linked to the massive difference between the efficiencies of both doses, and better results that the lower dose generated. Oxford and AstraZeneca didn’t explain why this happened.
The fact that two differently-designed trials in Brazil and Britain were used to arrive at the conclusion, didn’t help either.
Adding to the confusion, Oxford admitted some vials didn’t have the right concentration.
Those who received low doses were not above 55
Moreover, only 2,741 people received the half dose followed by the full dose, as compared to 8,895 getting full doses twice. This, experts believe, makes it difficult to ascertain if the efficacy is real.
Those in the low-dose category were aged under 55, meaning they have a stronger immune response.
This could become a problem when AstraZeneca applies for emergency use approval.
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