COVID-19 Vaccine AstraZeneca - Update

09 April 2021

9 April 2021

The Australian Technical Advisory Group on Immunisation (ATAGI) has released an updated statement on a specific clotting condition reported after COVID-19 vaccination. This condition has been named ‘thrombosis with thrombocytopenia syndrome’ (TTS).

ATAGI recommendations are as follows:

  • ‘ATAGI recommends that the COVID-19 vaccine by Pfizer (Comirnaty) is preferred over COVID-19 Vaccine AstraZeneca in adults aged under 50 years. This recommendation is based on the increasing risk of severe outcomes from COVID-19 in older adults (and hence a higher benefit from vaccination) and a potentially increased risk of TTS following AstraZeneca vaccine in those under 50 years.
  • COVID-19 Vaccine AstraZeneca can be used in adults aged under 50 years where the benefits are likely to outweigh the risks for that individual and the person has made an informed decision based on an understanding of the risks and benefits.
  • People who have had the first dose of COVID-19 Vaccine AstraZeneca without any serious adverse effects can be given the second dose, including adults under 50 years.’

Doctors are asked to:

  • Read the ATAGI AstraZeneca statement ‘ATAGI statement on AstraZeneca vaccine in response to new vaccine safety concerns’ (or
  • Be aware Pfizer (Comirnaty) is the preferred vaccine in adults aged under 50 years, however, the AstraZeneca vaccine can still be used in this age group when benefits are likely to outweigh the risks for that individual and informed consent is given. Provide adults receiving AstraZeneca vaccine with the current consumer medicine information (or
  • Continue to provide COVID-19 vaccination.
  • Ensure informed consent is undertaken when administering any vaccine.
  • Do not administer COVID-19 vaccine in persons who have a past history of central venous sinus thrombosis (CVST) or heparin induced thrombocytopenia (HIT), until further information is available.
  • Be alert for signs of TTS in persons who have received the COVID-19 vaccine AstraZeneca 4-20 days earlier including: new, severe or persistent headache not settling with analgesia, features of raised intracranial pressure (acute severe headache, vomiting, confusion), focal neurological deficits and/or seizures, or other significant symptoms e.g. severe abdominal pain.
  • Be alert for any persistent unexpected or severe adverse event following immunisation (AEFI).
  • Report severe or unexpected AEFI to SA Health
  • Advise patients of the common side effects of COVID-19 vaccine AstraZeneca (fever, sore muscles, tiredness and headache), their timing (usually start within 24 hours of vaccination and last for 1-2 days) and the importance of seeking medical care if symptoms are severe, unusual or persistent.

Doctors with patients with suspected TTS after AstraZeneca vaccine are asked to:

  • Refer to a hospital emergency department any patient with suspected CVST or other TTS.
  • Take initial investigations: full blood count (to look for thrombocytopenia), D-dimer, fibrinogen, and imaging as clinically indicated.
  • Consult with the haematologist on call if screening tests suggest HIT-like thromboses.
  • Do not give these patients heparin or platelet transfusions.

Dr Louise Flood – Director, Communicable Disease Control Branch

For all enquiries please contact the CDCB on 1300 232 272