AZD1222 is the vaccine developed by the University of Oxford, UK, and the pharma company AstraZeneca. After Moderna and Pfizer and BioNTech have published first very positive results from their ongoing Phase 3 studies, an interim analysis of clinical trials of AZD1222 also shows, according to a press release, that the vaccine is highly effective in preventing COVID-19. No hospitalizations or severe cases of the disease were reported in participants who received the vaccine. In total, there were 131 cases of COVID-19 in the interim analysis.
The vaccine is more effective when half a dose is administered first and a full dose a month later (90 %) than when two full doses are administered (62 %). This has caused discussions; AstraZeneca has so far not given a scientific explanation, only speculations. It could be possible, for example, that lower vaccine doses could better stimulate T cells, which support the production of antibodies. AZD1222 was well tolerated across both dosing regimens.
AstraZeneca announced that it will immediately prepare to submit the data to authorities around the world for conditional or early approval. The company plans to apply to the World Health Organization (WHO) for an Emergency Use Listing to speed up vaccine availability in low-income countries, and to submit a full analysis of interim results for publication in a peer-reviewed journal.
The global trials are evaluating participants aged 18 years or over from diverse racial and geographic groups who are healthy or have stable underlying medical conditions. The vaccine can be stored, transported, and handled at normal refrigerated conditions (2-8 °C) for at least six months and administered in existing health care facilities.
AZD1222 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.
- AstraZeneca, Cambridge, UK
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