ATAGI met on Wednesday 19 May 2021 to review the latest developments relating to the AstraZeneca COVID-19 vaccine and Thrombosis and Thrombocytopenia Syndrome (TTS) cases in Australia and overseas.
ATAGI considered an update from the TGA on current confirmed cases and those under investigation. Read the latest TGA statement on TTS cases.
ATAGI considered updated estimates of risk of TTS by age group in Australia and note that 20 cases have been confirmed and a further 3 are considered probable in around 1.5 million doses of COVID-19 Vaccine AstraZeneca given up to 5 May 2021. Although estimates of risk based on small numbers of cases are imprecise, the risk of TTS is estimated in Australia at around:
- 2.8 per 100,000 in those <50 years; and
- 1.4 per 100,000 in those ≥50 years.
Of the cases of TTS reported after vaccination with the AstraZeneca COVID-19 Vaccine in Australia, one of these patients had a fatal outcome. All other patients are stable or recovering.
It is difficult to compare rates of TTS with those in other countries due to differences in case definition and assessment, but the rates reported in Australia are broadly similar to those reported in the UK and Europe. However, the cases seen in Australia have presented somewhat differently to those in the UK and Europe, which may reflect the high case ascertainment and early case detection in Australia.
Clinical awareness of TTS is high and suspected cases are rapidly investigated in Australia: this may explain why the majority of Australian cases have recovered or are expected to recover. Notwithstanding this, ATAGI also notes that additional data is needed to understand causal relationship for cases that are under investigation.
TTS can now be treated effectively. The Thrombosis and Haemostasis Society of Australia and New Zealand (THANZ) have developed guidance on identification and treatment of TTS.