March 1, 2021

this is how the AstraZeneca and Oxford vaccine reached 90% efficacy

This Monday, the Anglo-Swedish laboratory AstraZeneca and the British University of Oxford released in a press release the first results of the study of phase 3 of their vaccine, which showed that has an average efficiency of 70.4%. But they also revealed that the vaccine had a superior efficacy of 90% after inoculating a half dose, followed by a full dose a month later, to a group of participants.

Why the Oxford and AstraZeneca COVID Vaccine May Go from 70% to 90% Efficacy and Other Keys to Your Early Data

Why the Oxford and AstraZeneca COVID Vaccine May Go from 70% to 90% Efficacy and Other Keys to Your Early Data

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Is about a find that has surprised to scientists, who have not yet been able to fully explain why the initial half dose has generated better protection, but believe that it may be because the immune system is activated differently. “It’s surprising, but it doesn’t seem crazy to me that your immune system reacts a little bit when you give it a lower dose and then when you give it a second higher dose, it develops a much bigger response. we do not wait. That is also why studies are done: to discover things that may seem counterintuitive “ he says in an interview with Spanish neurologist Carlos Estévez Fraga, who participated in clinical trials at his University College London (UCL) hospital as an adjunct investigator.

What AstraZeneca has explained is that the trials reached 90% efficacy by mistake, thanks to a stroke of good luck, Reuters reported. “The reason we use the half dose is a fluke,” Mene Pangalos, head of non-cancer research and development at the British laboratory, told the news agency.

In late April, university researchers administered the first doses to trial participants in Great Britain. Soon, Reuters reports, they noticed that anticipated side effects, such as fatigue, headaches or arm aches, were milder than expected, the researcher indicates.

“So we went back and checked (…) and discovered that they had spent half the dose of the vaccine,” said Pangalos, who explains that instead of restarting the trial, the researchers decided to continue with the half dose and administer the full booster dose at the scheduled time.

About 2,700 people received the half dose and then the full dose four weeks later, and data provided by AstraZeneca shows that 90% were protected. A larger group were given the two full doses as planned, resulting in an efficacy of 62%, leading to an overall efficacy of 70% in both dosing patterns.

According to Sarah Gilbert, a professor at the University of Oxford who led the research, such difference could be because “giving a small amount of the vaccine to start and follow with a large amount is a better way to kick the immune system into action and give us a stronger and more effective immune response “, The Guardian reports.

Professor Andrew Pollard, director of the Oxford Vaccine Group and lead investigator on the trial, added: “What we don’t know at this point is whether that difference is in the quality or quantity of the immune response. And that’s something that we will investigate in the next few weeks. ” In the Oxford University statement, Pollard stressed that if that regimen (half plus a whole dose) were used, “more people could be vaccinated with the planned vaccine supply.”

On November 19, researchers reported that Phase 2 demonstrated that their vaccine is safe, with few side effects, in healthy people even over 70 years of age and elicits an immune response in all age groups. The scientists point out that more studies should be done on the safety of the preparation in people with previous pathologies and different origins.

UK Health Minister Matt Hancock announced Monday that the British drug regulator will analyze the combination of doses of the Oxford and AstraZeneca vaccine that has been 90% effective. Speaking to the BBC, the minister indicated that the Medicines and Health Products Regulatory Agency (MHRA), under his ministry, will shortly examine whether it is feasible and effective to use the preparation in this way.


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