Not confidence-inducing: AstraZeneca messed up its clinical trial of Oxford’s vaccine, giving the first few thousand volunteers only half of what they’d planned as the first dose. But that turned out 90% effective compared to only 62% effective for the planned two full doses.
From The Guardian:
Participants given first shot at half strength by mistake were found to be better protected
Jessica Murray and agency
Mon 23 Nov 2020 18.24
The Oxford University and AstraZeneca vaccine trials reached 90% efficacy by accident thanks to the “serendipity” of an error that led to some participants receiving half doses, it has emerged.
On Monday scientists revealed that the Oxford vaccine had an overall efficacy of 70%, but could be around 90% effective when administered as a half dose followed by a full dose a month later.
“The reason we had the half dose is serendipity,” said Mene Pangalos, executive vice-president of biopharmaceuticals research and development at AstraZeneca.
Yes, he is Dr. Pangalos.
When university researchers were distributing the vaccine at the end of April, around the start of Oxford and AstraZeneca’s partnership, they noticed expected side effects such as fatigue, headaches or arm aches were milder than expected.
“So we went back and checked … and we found out that they had underpredicted the dose of the vaccine by half,” said Pangalos.
Instead of restarting the trial, he said researchers decided to continue with the half dose and administer the full dose booster shot at the scheduled time.
About 3,000 people were given the half dose and then a full dose four weeks later, with data showing 90% were protected. In the larger group, who were given two full doses also four weeks apart, efficacy was 62%.
It’s all for the best in this best of all possible worlds, reported Dr. Pangalos
Scientists said they still could not fully explain why the half dose gave better protection, but said it may be that it triggers the immune system differently.
How small was the sample size for this error that worked out well?
One issue was that due to the blinding process, they went quite a few months without knowing that their mistaken dosage was doing better in the trial. I presume they will now switch to this new pattern, but who knows how long that will take to get more results.