Patient Information on thrombosis with thrombocytopenia syndrome (TTS)


What is thrombosis with thrombocytopenia syndrome (TTS)?

  • This is a very rare side effect of the AstraZeneca vaccine. The condition is an immunological response which can cause thrombosis (blood clotting) and/or thrombocytopenia (low blood platelet counts). It can occur at different parts of the body, including the brain and in the abdomen.

When does TTS typically occur?

  • TTS onset occurs around 4 to 42 days (most commonly 4 to 30 days) following vaccination.

How common is TTS?

  • TTS is very rare. For ages over 60, it is estimated to affect 1.7 per 100,000 people. While for those under 60, the estimated rate is 2.6 per 100,000. It is more common in younger age groups.

How fatal is TTS?

  • TTS is a treatable condition. The overall case fatality rate in Australia is approximately 3%. (6 reported deaths in 7,000,000 vaccinations)

What symptoms does TTS usually cause?

TTS can cause a variety of symptoms which can include:

  • A severe persistent headache which appears at least 4 days after vaccination, does not improve with simple painkillers, may be worse when lying down, accompanied by nausea and vomiting
  • Neurological symptoms such as blurred vision, difficulty with speech, drowsiness, seizures.
  • Shortness of breath
  • Chest pain
  • Swelling in your leg
  • Persistent abdominal (belly) pain
  • Tiny blood spots under the skin away from the site of injection

If you have very severe symptoms, you should go to the Emergency Department.

If milder symptoms or unsure, consult your usual doctor.

You will get a blood test done to help the diagnosis, as early treatment improves outcomes.