CMAAO Coronavirus Facts and Myth Buster: Oxford Vaccine |
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CMAAO Coronavirus Facts and Myth Buster: Oxford Vaccine
Dr KK Aggarwal,  28 November 2020
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With input from Dr Monica Vasudev

1170:    India is expected to grant Pune’s Serum Institute of India (SII) with the emergency use authorization of Oxford and AstraZeneca’s COVID-19 vaccine if the pharmaceutical company receives such an approval from the UK government, Niti Aayog member Vinod Paul stated.  The vaccine is in its third and final phase of clinical trials in India, and if everything goes as planned, the vaccine may be ready for distribution by January or February next year. Earlier this week, the vaccine produced a robust immune response in older adults, thus raising hopes that it can protect the age groups most at risk from the viral disease.

AstraZeneca has announced that an early analysis of some of its late-stage clinical trials revealed that the vaccine was 70.4% effective on average and potentially up to 90% effective in preventing COVID-19. It is the third major vaccine developer that has announced promising results.  An early analysis of data from late-stage clinical trials noted the vaccine to be either 62% or 90% effective, depending on the manner in which the doses were given.

Unlike some other leading vaccine candidates, the AstraZeneca candidate can be quickly produced in large quantities, will cost only a few dollars per dose and is also easy to store for long periods of time. This could considerably increase the number of countries and people having access to the vaccine. The varying effectiveness of AstraZeneca’s vaccine pointed to differences in how doses were administered in the late-stage trials. The dosing plan that was found to be 90% effective had study participants receiving a half-dose of the vaccine, followed by a full dose a month later. The vaccine appeared to be less effective when people were given a standard full dose upfront, followed by another full dose a month later. On average, the vaccine was found to be 70% effective. The analysis, which evaluated data from participants in Britain and Brazil, did not turn up any serious safety concerns that were confirmed to be related to the vaccine. The vaccine had come under global scrutiny after the drug maker temporarily halted its trials in September after a participant in Britain developed a neurological illness.

Oxford and AstraZeneca stated that they would submit the trial data to regulators in Britain, the European Union and Brazil and would seek emergency authorization to initiate the distribution of the vaccine in those places. British and European Union regulators are conducting rolling reviews of the vaccine, which could speed up the authorization process.

Less than 2,800 participants in the clinical trials received the smaller first dose that yielded the strong results. This sample size is much smaller than that in Pfizer and Moderna trials.

The AstraZeneca vaccine uses a weakened version of a chimpanzee adenovirus as a delivery vehicle to carry the coronavirus genes into human cells. This trains the immune system to fight subsequent attacks from the actual coronavirus.

The data released came from Phase 2/3 clinical trial in Britain and its Phase 3 clinical trial in Brazil. The participants were randomized to receive either the coronavirus vaccine or a meningitis vaccine as a control, followed by a booster shot of the coronavirus vaccine, the meningitis vaccine or a placebo about four weeks later. Professor Pollard stated that the Oxford scientists expected to submit the results for publication in a peer-reviewed journal within 24 hours.

A vaccine using the technology behind AstraZeneca’s candidate has never been approved. But the approach has been studied before, particularly in a small 2018 study of an experimental vaccine against the virus that causes Middle East respiratory syndrome, or MERS. That virus is related to SARS-CoV-2. [Source:;]


Dr KK Aggarwal

President CMAAO, HCFI and Past National President IMA

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