Oxford-AstraZeneca Covid-19 Vaccine Error

Recently, companies involved in the making of COVID-19 vaccines Pfizer-BioNTech, Oxford-AstraZeneca, and Moderna announced the efficacy rates of their potential Covid-19 vaccines BNT162b2, AZD1222, and mRNA-1273, respectively. This is a good development to see the efficiency of these probable COVID-19 vaccines but a “dosing error” by Oxford-AstraZeneca has come to light which now put everybody in doubt over the authenticity of the efficacy of the company’s vaccine.

What is Oxford-AstraZeneca COVID-19 Vaccine Error?

AstraZeneca announced the efficiency results of its vaccine on November 23, 2020. The company said that two different dosing regimens of its vaccine have shown efficacy and one of them is showing a better profile. The company also claimed that there were no hospitalizations or severe cases of COVID-19 in participants who were treated with AZD1222. AstraZeneca highlighted that one dosing regimen of the vaccine has shown 90% efficacy when AZD1222 was given as a half dose, followed by a full dose at least one month apart, and the second dosing regimen has shown 62% efficacy when given as two full doses at least one month apart. The overall analysis of both dosing regimens has resulted in an average efficacy of 70% of the vaccine.

After this announcement, Moncef Slaoui, head of the US Operation Warp Speed program, who is looking after the vaccine program in America, claimed that most of the participants under trials received the regimen of two full doses were from the age group of 55 years and over. The regimen of full dose showed 62% efficacy in comparison to the half dose regimen that was tested mainly on the younger age group and showed 90% efficacy.

Now, AstraZeneca is facing questions over the efficacy rate.

What led to this error?

Mene Pangalos, the Head of AstraZeneca’s non-oncology research and development, said that while initiating a partnership with Oxford University in April 2020, the researchers of the university were administering doses to trial participants in Britain. During those trials side effects like headaches, arm aches, fatigue, etc. were seen so we rechecked everything and found that the dose of the vaccine was under-predicted. So, a full-dose regimen was started later.

The University of Oxford said that they have used different methods of measuring the concentration of the COVID-19 vaccine.


It is a British–Swedish pharmaceutical and biopharmaceutical company which was founded in 1999. It is headquartered in Cambridge, England.