How AstraZeneca vaccine works
MKHIZE: ANNNOUNCEMENT OF 1.5M DOSES WELCOME After vaccination, protein is produced priming immune system to attack virus.
Health Minister Dr Zweli Mkhize’s announcement 1.5 million doses of the AstraZeneca Covid-19 vaccine (formerly AZD1222) has been widely welcomed.
We break down where it’s from, who is making it, and how it works.
How AstraZeneca works
AZD1222 was co-invented by the University of Oxford and its spinout company, Vaccitech. It uses a replication-deficient chimpanzee viral vector based on a weakened version of a common cold virus (adenovirus) which 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.
According to gavi.org, viral vector-based vaccines differ from most conventional vaccines in that they don’t actually contain antigens (molecules capable of stimulating an immune response), but rather use the body’s own cells to produce them.
They do this by using a modified virus (the vector) to deliver genetic code for antigen, in the case of Covid-19 spike proteins found on the surface of the virus, into human cells.
By infecting cells and instructing them to make large amounts of antigen, which then trigger an immune response, the vaccine mimics what happens during natural infection with certain pathogens – especially viruses.
Who is making it
AstraZeneca has partnered with Serum Institute of India (SII), the world’s largest vaccine manufacturer, for the supply of the vaccine to the Indian government but also to a large number of poor countries.
Vaccine alliance Gavi and the Bill & Melinda Gates Foundation will accelerate the manufacture and delivery of up to 100 million doses of safe and effective vaccines for India and low-and middle-income countries as part of the Gavi Covax AMC, a mechanism within the Covax facility.
The Wall Street Journal reported in August the doses would be priced at less than $3 (about R45) per dose. It also reported the SII is the “go-to vaccine supplier for the World Health Organisation (WHO) and others and produces 1.5 billion doses of other vaccines every year, making it the largest in the world by volume”.
What is Covax
It's one of three pillars of the Access to Covid-19 Tools (ACT) Accelerator, which was launched in April by the WHO, the European Commission and France in response to this pandemic.
It brings together governments, global health organisations, manufacturers, scientists, private sector, civil society and philanthropy, with the aim of providing innovative and equitable access to Covid-19 diagnostics, treatments and vaccines. The Covax pillar is focussed on the latter.
“All participating countries, regardless of income levels, will have equal access to these vaccines once they are developed," said Gavi chief executive Dr Seth Berkley.
It mimics what happens during natural infection