Oxford vaccine up to 90% effective, interim analysis shows

A COVID-19 vaccine developed by the University of Oxford and AstraZeneca plc is up to 90% effective, interim analysis shows.

Data from its phase three trials shows ChAdOx1 nCoV-2019 is effective at preventing COVID-19 and offers a high level of protection.

Preliminary data indicates it is 70.4% effective and 90% effective if administered at a half dose and then at a full dose or 62% effective if administered in two full doses.

Data also suggests the vaccine can prevent transmission of the virus, evidenced by lower rates of asymptomatic infection in participants.

More than 24,000 people volunteered for the trial in the UK, Brazil and South Africa, including 996 in Oxford.

Additional cases are expected to accrue by the time of the final analysis and future analyses will determine the duration of protection. No serious safety events related to the vaccine have been identified.

Oxford will now support AstraZeneca in submitting data to regulators across the world for emergency use. Many regulators have been reviewing the data on a rolling basis during the trial.

AstraZeneca has international agreements in place to supply three billion doses on a not-for-profit basis for the duration of the pandemic across the world, and in perpetuity to low and middle-income countries.

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’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."

Pascal Soriot, Chief Executive Officer, AstraZeneca, said: “Today marks an important milestone in our fight against the pandemic.

“This vaccine’s efficacy and safety confirm that it will be highly effective against COVID-19 and will have an immediate impact on this public health emergency.

“Furthermore, the vaccine’s simple supply chain and our no-profit pledge and commitment to broad, equitable and timely access means it will be affordable and globally available supplying hundreds of millions of doses on approval.”

The trials will now continue to final analysis. Further trials are being conducted in the United States, Kenya, Japan and India and the trial team expect to have under 60,000 participants by the end of the year.

The data is also being submitted for independent scientific peer review and publication.

The Oxford vaccine (ChAdOx1 nCoV-19) 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 been researched and used extensively for decades and have the significant benefit that they are stable, easily manufactured, transported and stored at domestic fridge temperature (2-8 degrees C).

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 rapidly.