A Western Australian woman in her 40s has become the second person in Australia to develop a rare clotting disorder after being given the AstraZeneca COVID-19 vaccine.

The Vaccine Safety Investigation Group has concluded the case of thrombosis with thrombocytopenia is likely linked to the injection.

The woman is in a stable condition in hospital where she is receiving treatment.

Fears about rare blood clots prompted the federal government to revise its use of the AstraZeneca vaccine last week.

Australians under the age of 50 have been urged to avoid getting the AstraZeneca COVID-19 vaccine where possible.

The Pfizer vaccine is now the preferred treatment for Australians under 50.