University of Oxford developed 90% effectiveness of COVID-19 vaccine by accident

The COVID-19 vaccine developed by the University of Oxford and AstraZeneca could be 90 percent effective after receiving half-dose due to error, giving public health officials hope that they may soon have an effective and cheaper vaccine which will be easier to distribute.


The participants were given two high doses, which showed 62 percent efficiency, but it rose to 90 percent when they were given a half dose, followed by a high one.

“The reason we had the half dose is serendipity,” said Mene Pangalos, executive vice-president of biopharmaceuticals research and development at AstraZeneca.

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 researchers decided to continue with the half dose and administer the full dose booster shot at the scheduled time, he said.

Scientists said they still could not fully explain why the half dose gave better protection but said that it may have triggered the immune system differently. Prof Sarah Gilbert from Oxford University, who led the research, said, “It could be that by giving a small amount of the vaccine to start with and following up with a big amount, that’s a better way of kicking the immune system into action and giving us the strongest immune response and the most effective immune response.”

Prof Andrew Pollard, director of the Oxford Vaccine Group and chief investigator of the trial added,  “What we don’t know at this moment is whether that difference is in the quality or the quantity of immune response. And that’s something we’re going to be digging into over the next weeks.”

The vaccine still needs to be approved by the Medicines and Healthcare products Regulatory Agency but could be made available in the coming weeks if given the go-ahead.

The UK government has already pre-ordered 100 million doses of the Oxford vaccine, reported BBC.