To aspirate or not to aspirate? Considerations for the COVID-19 vaccines

Area of Science:

• Immunology
• Vaccinology
• Public Health

Background:

• Intramuscular vaccination guidelines previously did not recommend syringe aspiration due to insufficient evidence of benefit.
• Emerging in vivo data suggest potential risks associated with accidental intravascular administration of vaccines.
• Rare adverse events, including myocarditis (mRNA vaccines) and thrombocytopenia/coagulopathy (adenoviral vector vaccines), have been reported post-COVID-19 vaccination.

Purpose of the Study:

• To evaluate the potential benefit of syringe aspiration in reducing the risk of severe adverse reactions following COVID-19 vaccination.
• To assess the applicability of syringe aspiration in the context of ongoing global vaccine administration, including booster doses.

Main Methods:

• Review of in vivo evidence regarding vaccine administration routes and associated risks.
• Analysis of reported rare adverse events following COVID-19 vaccination.
• Consideration of the precautionary principle in vaccination techniques.

Main Results:

• Intravenous injection of mRNA vaccines may be linked to myocarditis.
• Intravascular administration of adenoviral vector vaccines may be associated with thrombocytopenia and coagulopathy.
• Syringe aspiration is a simple technique that can potentially mitigate the risk of accidental intravascular vaccine injection.

Conclusions:

• Syringe aspiration, despite potentially increasing local pain, offers a method to decrease the risk of intravascular vaccine introduction.
• The potential to reduce severe reactions makes syringe aspiration a relevant consideration for mRNA and adenoviral COVID-19 vaccines.
• Implementing syringe aspiration aligns with the precautionary principle for widespread vaccine administration, including boosters.