Recently, the companies making of COVID-19 vaccines Pfizer-BioNTech, Oxford-AstraZeneca, and Moderna announced the efficacy rates of their potential vaccines BNT162b2, AZD1222, and mRNA-1273, respectively. This is a good development to see the efficiency of these probable SARS-CoV-2 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.

AstraZeneca SARS-CoV-2 Vaccine Error

The AstraZeneca announced the efficiency results of its vaccine on 23 November 2020. AstraZeneca said that two different dosing regimens of its SARS-CoV-2 vaccine have shown efficacy and one of them is showing a better profile. AstraZeneca also claimed that there were no hospitalizations or severe cases of SARS-CoV-2 in participants who were treated with AZD1222. The company highlighted that one dosing regimen of the vaccine has shown 90 per cent efficacy when AZD1222 was given as a half dose, followed by a full dose at least 30 days apart, and the second dosing regimen has shown 62 per cent efficacy when given as two full doses at least 30 days apart. The overall analysis of both dosing regimens has resulted in an average efficacy of 70 per cent of the Covid-19 vaccine.

After this announcement, Moncef Mohamed Slaoui, head of the United States Operation Warp Speed program, who is looking after the vaccine program in USA, 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 per cent efficacy in comparison to the half dose regimen that was tested mainly on the younger age group and showed 90 per cent efficacy.

Now, The company is facing questions over the efficacy rate.

causes of error

British neuroscientist Sir Menelaos Nicolas 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 Oxford 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 Covid-19 vaccine was under-predicted. So, a full-dose regimen was started later.

The Oxford said that they have used different methods of measuring the concentration of the vaccine.


AstraZeneca plc  is a British–Swedish pharmaceutical and biopharmaceutical company. AstraZeneca was founded in 1999 and headquarter located in England’s Cambridge. Oxford-AstraZeneca Covid-19 Vaccine Error Oxford-AstraZeneca Covid-19 Vaccine Error