Oxford COVID-19 vaccine 70 percent effective, interim data shows

The University of Oxford and AstraZeneca COVID-19 vaccine candidate, ChAdOx1 nCoV-2019, prevented infection from SARS-CoV-2 in two dosing regimens.

COVID-19 vaccines

Interim trial data from the Phase III study of the University of Oxford, UK, and AstraZeneca COVID-19 vaccine candidate has shown that it is 70 percent effective.

The vaccine, called ChAdOx1 nCoV-2019, was successful at preventing infection from SARS-CoV-2 in two dosing regimens. Researchers found that one dosing regimen was 90 percent effective, where a halved dose was administered followed by a second standard dose while the other was 62 percent effective, using two full doses. 

The researchers also reported that there were no hospitalised or severe cases in anyone who received the vaccine. 

The clinical trials, enrolling over 24,000 participants from diverse racial and geographical groups in the UK, Brazil and South Africa, will now continue to final analysis. Further trials are being conducted in the US, Kenya, Japan and India and the trial team expect to have under 60,000 participants by the end of the year. These trials will provide regulators with further information about the efficacy and safety of ChAdOx1 nCoV-2019, including its ability to both protect against and stop the transmission of COVID-19.

Professor Andrew Pollard, Director of the Oxford Vaccine Group and Chief Investigator of the Oxford Vaccine Trial, said: “These findings show that we have an effective vaccine that will save many lives. Excitingly, we have found that one of our dosing regimens may be around 90 percent effective and if this dosing regimen 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.”

The vaccine is made from a weakened version of a common cold virus (adenovirus), that has been genetically changed so that it is impossible for it to grow in humans. 

Adenovirus vaccines have the significant benefit that they are stable, easily manufactured, transported and stored at domestic fridge temperature (2-8°C). The developers say this means they can be easily distributed using existing medical facilities such as doctor’s surgeries and local pharmacies, allowing for the vaccine, if approved, to be deployed very rapidly. 

Oxford and AstraZeneca will now submit both the interim Phase III efficacy data and the extensive safety data to all regulators across the world, including in the UK, Europe and Brazil for independent scrutiny and product approval, including for emergency use. Many of these regulators have been reviewing the trial data on a rolling basis during the trial.

In parallel, Oxford is submitting the full analysis of the Phase III interim data for independent scientific peer review and publication.