Interim analysis of the phase III programme conducted by Oxford University with its COVID-19 vaccine candidate AZD1222 showed that the vaccine is effective at preventing COVID-19, with no severe cases and no hospitalisations more than 21 days after the first injection. The results were published in The Lancet today.
The interim analysis for efficacy was based on 11,636 participants accruing 131 symptomatic infections from the phase III UK and Brazil trials conducted by Oxford University.
As previously announced on 23 November 2020, the primary efficacy endpoint of the programme statistical plan, based on the pooling of two dosing regimens, showed that the vaccine is 70.4% effective at preventing symptomatic COVID-19 occurring more than 14 days after receiving two doses of the vaccine.
Further analysis of the efficacy regimens showed that when the vaccine was given as two full doses, vaccine efficacy was 62.1% and 90.0% in participants who received a half dose followed by a full dose.
Vaccine efficacy was also assessed on the secondary endpoint of early prevention of severe disease after the first dose. There were no hospitalisations or severe cases of COVID-19 more than 21 days after the first dose of the vaccine. Ten participants in the control group were hospitalised due to COVID-19, among whom two were assessed as severe, including one fatal case.
More data will continue to accumulate as part of the upcoming primary analysis and further follow-up, refining the efficacy reading and characterising vaccine efficacy over a longer period of time.
The safety data published so far is from over 20,000 participants enrolled across four clinical trials in the UK, Brazil and South Africa. The overall reported rates of serious adverse events were 0.7% in the vaccine group and 0.8% in the control group.
The company is seeking Emergency Use Listing from the World Health Organization for an accelerated pathway to vaccine availability in low-income countries.
In addition to the Oxford-led programme, AstraZeneca is conducting a large study in the US and globally. In total, Oxford University and AstraZeneca expect to enrol more than 60,000 participants globally.
The company is also 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, said AstraZeneca in a press release.
The vaccine can be stored, transported and handled at normal refrigerated conditions (2-8 degrees Celsius/ 36-46 degrees Fahrenheit) for at least six months and administered within existing healthcare settings.
AZD1222 was co-invented by the University of Oxford and its spin-out company, Vaccitech. It 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.