Question Number: 196
PDR Number: SQ22-000250
Date Submitted: 24/02/2022
Department or Body: Department of Health
Some scientific reports have proposed that inadvertent injection of a COVID-19 vaccine into a blood vessel may be a contributing cause of serious adverse events following immunisation, such as thrombosis with thrombocytopenia syndrome (TTS) and myocarditis.
Based on a review of the available evidence, Australian Technical Advisory Group on Immunisation (ATAGI) does not recommend routinely aspirating (drawing back) needles before injection. This practice was rejected some decades ago, due to several disadvantages including prolonging the procedure, potentially associated pain, and increasing the risk of needle-syringe disconnection.
ATAGI has reviewed the available evidence and considers injection technique highly unlikely to be a contributor to these adverse events for several reasons:
• The majority of cases of TTS occur after the first dose of a viral vector vaccine AstraZeneca. The majority of myocarditis cases occur after the second dose of the mRNA vaccines such as Pfizer or Moderna. If intravascular injection was an important contributor, there would not be this differential distribution of cases by vaccine dose.
• Direct injection into a blood vessel is unlikely in recommended injection sites.
• TTS typically occurs some days or even weeks after vaccination, which does not fit with the proposed theory of direct vascular injury which occurs early in animal models.
This information is available in ATAGI’s clinical guidance, available at: www.health.gov.au using the search term “ATAGI clinical guidance” and navigating to the section titled ‘transport, storage and handling’.
