Oxford-AstraZeneca Says COVID-19 Vaccine Shows 62-90% Efficacy

University of Oxford's COVID-19 vaccine built in collaboration with AstraZeneca showed an average of 70 per cent effectiveness in its interim results making it the third vaccine candidate showing promising results. The researchers followed two different dosing regimens and combined results of Phase II/III trials and Phase III trials among 11,636 participants to obtain these results.

While both the regimens administered two doses of the vaccine, the dosage varied. Around 2,741 of the participants from the 12,390 participants in UK who received one half dose (~2.5 x1010 viral particles) and a full dose (~5x1010 viral particles) of AZD1222 were assessed for interim analysis. This dosing regimen showed a 90 per cent efficacy. From the 10,300 participants in Brazil, around 8,895 who received two full doses were studied for the interim analysis. It is notable that the vaccine efficacy for two full doses stood at 62 per cent which is lower than the one and a half dosage.

None of the 131 participants who tested positive for COVID-19 reported records of hospitalisation or any severe cases of COVID-19. An independent Data and Safety Monitoring Board approved that the vaccine has managed to deliver its primary endpoint of protecting from contracting COVID-19 in 14 days or more after receiving two doses of the vaccine.

The pharmaceutical further suggests that no serious safety concerns were reported related to the vaccine. This suggests that the adverse reaction noted in September owing to which the trials were halted across the world was administered the placebo.

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Professor Andrew Pollard, Chief Investigator of the Oxford Vaccine Trial at Oxford, said: "These findings show that we have an effective vaccine that will save many lives. Excitingly, we've found that one of our dosing regimens may be around 90% effective and if this dosing regime is used, more people could be vaccinated with planned vaccine supply. Today's announcement is only possible thanks to the many volunteers in our trial, and the hard working and talented team of researchers based around the world."

AstraZeneca plans to approach the World Health Organization for Emergency Use Listing to accelerate the process of making the vaccine available in low-income countries along with preparing for regulatory approval according to each country's needs. Oxford, on the other hand, is working on the full analysis of the interim results to get them published in an acclaimed peer-reviewed journal.

Clinical trials for the vaccine are ongoing in US, UK, Brazil, South Africa, Russia, Japan, India, Kenya, and other Latin American countries. The company intends to manufacture 3 billion doses globally by 2021 depending on regulatory approval.

The vaccine can be stored, transported and handled at normal refrigerated conditions (2-8 degrees Celsius/ 36-46 degrees Fahrenheit) for at least six months and administered within existing healthcare settings. It is suitable for existing health infrastructure and does not require cold storage unlike Pfizer's vaccine.

What is AZD1222

The vaccine uses a weakened adenoviral strain as a vector for the genetic material of the spike protein of SARS-CoV-2. After vaccination, the surface spike protein is produced, priming the immune system to attack the SARS-CoV-2 virus if it later infects the body.

Using Human Embryonic Kidney cells as a medium for vaccine growth, the vaccine is considered to be one of the frontrunners against COVID-19.