The efficacy of the coronavirus vaccine from AstraZeneca and the University of Oxford may be due in part to a dosing error.
In a press release on the effectiveness of the vaccine released on Monday, the dose of the vaccine candidate had the highest efficacy – up to 90% – for the group that received half the dose and then the full dose.
But the candidate vaccine was only 62% effective in the group receiving two full doses.
May Pangalos, head of AstraZeneca’s biopharmaceuticals research and development, admitted to Reuters on Monday that some participants received half the dose due to a dosing error and then the full dose.
In an interview with the New York Times published on Wednesday, Pangalos called it a “useful mistake.”
Oxford University said in a statement Wednesday that the concentration of the vaccine in some of the test vials was not appropriate. The university said the issue was discussed with regulators and they decided to complete the model phase hearing in two groups, according to the AP.
Experts say the low number of people in the low-dose group – some 2,741 – makes it difficult to know whether the effectiveness is statistically significant.
Furthermore, no one in the low dose group is over 55 years of age and younger people have stronger immunity than older people.
A spokesman for Oxford University told Euronews that “as a result of differences in the manufacturing process” the trial method at the first stage “showed a greater estimate of the dose on the new batch of vaccines, resulting in half the dose of the vaccine being administered as the first dose”.
After discussion with the regulator, two different concentrations were tested in Phase III.
Another area of confusion, said David Salisbury, a fellow at the World Health Program at Chatham House, is that in a press release, the results of both groups reach an oo0 percent effectiveness.
“You’ve taken two studies, for which different doses were used and came up with a combination that doesn’t represent any of the doses,” Salisbury told the AP. “I think a lot of people are having trouble with it.”
Researchers say that a small first dose may be more effective because you only need the right amount to get a good immune response.
Some have criticized AstraZeneca and Oxford for the lack of transparency in announcing the results.
“AstraZeneca / Ox Xford gets poor grades for transparency and hardness when they report vaccine trial results. This is not like Pfizer or Moderna where we had the protocol in advance and pre-determined preliminary analysis was noted,” said Natalie Deanist, Florida of Florida Assistant Professor.
“If they try to allow half a dose, they should wait until an attractive result is reached. Otherwise, we can land in the ‘evidence limbo’.”
More detailed results of the trial are expected to be provided to regulators who will decide whether to authorize the vaccine.
U.S. Monsef Sloy, who heads the coronavirus vaccine program, told reporters that U.S. officials are trying to determine what resistance the vaccine has given.
They may decide to revise the US to include half the dose in the Strazeneca study: “But we want it to be based on data and science,” he said.
Euronews has reached out to AstraZeneca for comment.
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