Oxford Covid vaccine is 90% effective, phase 3 interim analysis shows

Oxford’s COVID-19 vaccine is the third candidate to report high safety and efficacy over 90%, after Pfizer and Moderna Inc.

For the first and latest interim analysis of phase 3 trials, the team used data from over 24,000 volunteers from the UK, Brazil and South Africa. The data was collected till 4 November 2020.

According to its news release, Oxford University has submitted the complete analysis of phase 3 interim data for peer review and publication.

Trials are now expected to be held in the US, Kenya, Japan and India, with around 60,000 participants by year-end.  The team expects future analyses to also reveal the duration of protection that the vaccine affords.

On 18 November 2020, researchers had published a paper in The Lancet peer-reviewed journal saying that ChAdOx1 nCoV-19 was well-tolerated in older adults (aged 56-69 and 70 and above) and showed “similar immunogenicity across all age groups after a boost dose”.

Oxford University, in partnership with pharmaceuticals company AstraZeneca Plc, plans to supply three billion doses of ChAdOx1 nCoV-19 vaccine during 2021.

As part of the partnership between Oxford University and AstraZeneca, the vaccine will be available worldwide on a not-for-profit basis while the pandemic lasts, and on a not-for-profit basis in perpetuity to low- and middle-income countries. 

ChAdOx1 nCoV-19 (AZD1222) was co-invented by the University of Oxford and its subsidiary, Vaccitech. Oxford University’s Jenner Institute and Oxford Vaccine Group are conducting the trials, phase 3 of which began in May 2020.

National Institute for Health Research, UK Research and Innovation, the Bill & Melinda Gates Foundation, the Lemann Foundation, and the South African Medical Research Council are funding the trials.

ChAdOx1 nCoV-19 uses a modified adenovirus as a carrier or vector (read more: Vector vaccines). Adenovirus is one of many common cold viruses. It is often used as a vector to build vaccine immunity against other pathogens.

In ChAdOx1 n-CoV-19, the adenovirus is modified so that it doesn’t cause illness in humans but helps to administer the vaccine and trigger the immune system.

Here’s how it does this: the vaccine contains genetic material from the spike (S) protein of SARS-CoV-2 (the virus that causes COVID-19). Once inside the body, the genetic material helps to produce the S protein. The body recognises the S protein as foreign and the immune system attacks it. According to previous research, ChAdOx1 can trigger effective antibody and T-cell responses.

It can also have temporary side effects, such as fever, flu-like symptoms, headache or soreness at the injection site.

Importantly, the vaccine will avoid some logistical challenges: ChAdOx1 nCoV-19 vaccine can be stored in a refrigerator, at 2-8 degrees Celsius. This is significant, as this will make it possible to take the vaccine to all parts of the world, even places where freezers are difficult to find or power continuously.