After acknowledging a manufacturing error, University of Oxford and drugmaker AstraZeneca face mounting questions about their COVID-19 vaccine trial results.
Although an announcement by Oxford and AstraZeneca earlier this week showed that their shot was 70 percent effective in a late-stage study on average, the minimal information provided by the UK partners have sparked concerns, with some raising doubts as to whether US regulators will clear it for use.
Oxford and AstraZeneca had said their vaccine was 90 percent effective when a half-dose was given before a full-dose booster. Two full doses showed an efficacy of 62 percent. But the head of the US vaccine program known as Operation Warp Speed said the next day that the dose showing the higher level of effectiveness was tested in a younger population.
Oxford said in a statement that a difference in manufacturing processes contributed to later phases of the trials having a half-dose given instead of a full one. It was clarified with regulators when it was clear that a lower dosage was used and an agreement was reached to go forward with the two regimens, the statement said.
“The methods for measuring the concentration are now established and we can ensure that all batches of vaccine are now equivalent,” according to the university.
Astra shares rose 0.5 percent today after slumping 6.2 percent earlier in the week.
“The most likely explanation for the divergent efficacy in its interim analysis is either chance or patient demographics,” said experts. “Either way, approval based on current data means people will be inoculated with a vaccine the true efficacy of which is unknown.”
A spokesman for AstraZeneca said the trials were conducted “to the highest standards” and more analysis is being done to refine the efficacy reading.
After the vaccine candidates from American pharmaceutical companies Pfizer (who developed the vaccine in collaboration with German drugmaker BioNTech) and Moderna exhibited almost 95 percent, Oxford’s vaccine efficiency was met with a little disappointment as it showed an average of 70 percent efficacy. However, lower price and easy storage makes it the ideal choice for developing countries.