AZ and Oxford COVID-19 vaccine brings end of pandemic a little closer

AstraZeneca's production and manufacturing facility. (Source: AstraZeneca)

AZD1222 is 90% effective, cheap to produce and easy to store, distribute and administer

Positive high-level results from early Phase III clinical trials of AZD1222 in 24,000 volunteers in the UK and Brazil indicate the candidate vaccine was highly effective in preventing COVID-19.

Encouragingly, no hospitalisations or severe cases of the disease were reported in participants receiving the vaccine.

One dosing regimen showed vaccine efficacy of 90% when AZD1222 was given as a half dose, followed by a full dose at least one month apart. Another dosing regimen showed 62% efficacy when given as two full doses at least one month apart. The combined analysis from both dosing regimens resulted in an efficacy of 70.4%.

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.

An independent Data Safety Monitoring Board determined that the analysis met its primary endpoint showing protection from COVID-19 occurring 14 days or more after receiving two doses of the vaccine.

Setting this COVID-19 vaccine apart from the Pfizer/BioNTech and Moderna candidates is that it can be easily administered in existing healthcare systems, stored at fridge temperature (2–8 °C) for at least 6 months and distributed using existing logistics.

The vaccine, which was co-invented by the University of Oxford and its spin-out company Vaccitech, uses a replication-deficient chimpanzee viral vector based on a weakened version of a common cold virus (adenovirus) that causes infections in chimpanzees and contains the genetic material of the SARS-CoV-2 virus spike protein. 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.

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."

AstraZeneca is making rapid progress in manufacturing with a capacity of up to 3 billion doses of the vaccine in 2021 on a rolling basis, pending regulatory approval.