The vaccine uses a harmless, weakened animal virus (called a viral vector) that contains the genetic code for the coronavirus spike protein. Once this enters the body, it tells your cells to make copies of the spike protein. Your immune cells then recognise the spike protein as a threat and begin building an immune response against it. The vaccine does not contain any live virus, and it cannot give you COVID-19.1
The Therapeutic Goods Administration (TGA) provisionally approved the AstraZeneca COVID-19 vaccine for use in Australia on 15 February 2021 for people 18 years and over.1 5 The Australian Technical Advisory Group on Immunisation (ATAGI) recommends the AstraZeneca vaccine for people aged 60 and over and for people aged 18 to 59 in outbreak areas if they do not have immediate access to the Pfizer or Moderna COVID-19 vaccines.1
Real-world data has uncovered an extremely rare blood clotting syndrome called Thrombosis with Thrombocytopenia Syndrome (TTS) that is a rare side effect of the AstraZeneca vaccine. TTS typically occurs around 4 to 30 days after vaccination with AstraZeneca COVID-19 vaccine and while extremely rare, can be very serious and can cause long term disability and death.7 Current data indicates that TTS occurs in around 2 out of every 100,000 people who receive the first dose of the AstraZeneca COVID-19 vaccine. TTS appears to be far rarer following second doses, with data from the United Kingdom (UK) indicating a rate of 1.5 per million second doses.8
Specialists have already developed specific ways to treat TTS, including using anticoagulant (anti-clotting) medication — other than heparin — intravenous immunoglobulin (an infusion of antibodies into the person’s bloodstream) and prednisolone (a type of steroid). Now that doctors know how to recognise and treat TTS early, the chance of survival is very good. 11
Two doses of the AstraZeneca vaccine are required for maximum protection against COVID-19. People who have received the AstraZeneca vaccine may not be fully protected against COVID-19 until 7 to 14 days after the second dose.1 ATAGI and the TGA recommend 8 to 12 weeks (4 weeks at a minimum) between the first and second dose of AstraZeneca COVID-19 vaccine.