Oxford vaccine trialled in Southampton offers high level of protection, interim analysis shows

The University of Oxford, in collaboration with AstraZeneca plc, has announced interim trial data from its Phase III trials that shows its candidate vaccine, ChAdOx1 nCoV-2019, is effective at preventing COVID-19 (SARS-CoV-2) and offers a high level of protection.

Following the trial reaching the target for interim analysis, the independent Data and Safety Monitoring Board (DSMB) recommended that the team at Oxford conduct its first analysis on all the cases with data locked at 4 November 2020.

These preliminary data indicate that the vaccine is 70.4% effective, with tests on two different dose regimes showing that the vaccine was 90% effective if administered at a half dose and then at a full dose, or 62% effective if administered in two full doses.

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. The promising findings have been published in The Lancet.

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.’

More than 24,000 people volunteered for the trial in the UK, Brazil and South Africa, including over 700 from the Southampton area. Professor Saul Faust, Clinical Director of the NIHR Clinical Research Network Wessex, led the clinical trial in Southampton.

Oxford will now support AstraZeneca in submitting 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. The coordination of the programme and execution of the trials in the UK would not have been possible without the support of the National Institute for Health Research and UKRI.

These data also suggest that this half dose and full dose regime could help to prevent transmission of the virus, evidenced by lower rates of asymptomatic infection in the vaccinees, with further information to become available when trial data are next evaluated.

The interim Phase III data builds on Oxford’s phase I/II peer-reviewed trial results which have shown that the vaccine induces strong antibody and T cell immune responses across all age groups, including older adults, and has a good safety profile.

The Oxford vaccine (ChAdOx1 nCoV-19) is made from a virus, which is 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 very rapidly.