One lucky hit over a dosing mistake will pave the way for AstraZeneca and Oxford University to submit their Covid-19 vaccine for regulatory approval.
The British drug company said on Monday that the vaccine could be about 90% effective when administered as a half dose followed by a full dose a month later, citing data from late-stage studies in Britain and Brazil.
“The reason we got half the dose is serendipity,” Mene Pangalos, the head of AstraZeneca’s non-oncology research and development, told Reuters.
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A larger group that received two full doses – as planned – resulted in a 62% efficacy reading, resulting in an overall efficacy of 70% for both dosing patterns.
Around the time Astra started working with Oxford in late April, university researchers were administering doses to trial participants in Great Britain.
They soon noticed that expected side effects such as fatigue, headaches, or arm pain were milder than expected, he said.
“So we went back to check it … and we found that they predicted the dose of the vaccine by half,” Pangalos said.
He added that the company decided to continue with the half dose and to administer the full dose of booster injection at the scheduled time.