Is it true? Does the Vaxzevria (AstraZeneca) COVID-19 vaccine cause blood clots?

There has been a link established between the AstraZeneca vaccine and a very rare but serious side effect called thrombosis in combination with thrombocytopenia. There is a very low chance of this side effect, which may occur in around 4-6 people in every million after being vaccinated.

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Is it true?

Does the AstraZeneca COVID-19 vaccine cause blood clots?

Australia’s medical experts, the Australian Technical Advisory Group on Immunisation (ATAGI) have recently reviewed the data available on the incidence of rare blood clots after COVID-19 vaccination

There has been a link established between the AstraZeneca vaccine and a very rare but serious side effect called thrombosis in combination with thrombocytopenia

Age Estimated risk of TTS per 100,000
AstraZeneca vaccine doses (first dose)

<50 years

3.1

50-59 years

2.7

60-69 years

1.4

70-79 years

1.8

80+ years

1.9

  • * as at June 2021

The experts at ATAGI actively monitor cases of this syndrome. They have considered the risk of this rare side effect against the benefits of vaccination for different age groups.

They have noticed higher rates of this rare condition in people aged 50-59 years and recommend the Comirnaty (Pfizer) vaccine as the preferred vaccine for people under the age of 60. 

ATAGI also recommends people of all ages who have had the first dose of the AstraZeneca vaccine without serious adverse effects have their second dose of AstraZeneca.

For people aged 60 years or above, the benefits of vaccination, with any vaccine including AstraZeneca, clearly outweigh the risks of TTS. 

Learn more about the AstraZeneca vaccine and thrombosis in combination with thrombocytopenia.

With new COVID-19 vaccine developments every day, it’s normal to have questions or concerns, and possibly feel hesitant about getting a vaccine. That's why we're providing accurate, evidence-based answers to questions about COVID-19 vaccines.

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Last updated: 
4 September 2021

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