Early testing for blood clots in patients who had received the AstraZeneca Covid-19 vaccine led to them being treated successfully, new research led by an Irish team has shown.

These findings highlight the need for heightened awareness among doctors of the risk of blood clots.

Unusual blood clots with low blood platelets have been recognised as a very rare complication of the AstraZeneca vaccine. However, patients may not have all of the related symptoms when they initially present to medical services.

This work into the vaccine was led by researchers from the RCSI University of Medicine and Health Sciences and the National Coagulation Centre at St James’s Hospital.

They highlighted four patients who had experienced clotting complications induced by the vaccine (vaccine induced thrombotic thrombocytopenia or VITT).

Based on the current guidance, each patient could have been classified as a low likelihood for this syndrome when they presented to doctors. However, due to the increased awareness and clinical vigilance from the medical teams involved, all were sent for early testing and were then diagnosed and treated successfully.

According to Dr Michelle Lavin, lead author of the paper and a researcher at the Irish Centre for Vascular Biology and the RCSI School of Pharmacy and Biomolecular Science, while the risk of developing a blood clot from the vaccine is still far lower than the risk of developing clots from Covid-19, “it is imperative that clinicians are vigilant in detecting symptoms among vaccinated patients”.

“Our research has shown that current guidelines lack the sensitivity to detect early cases of vaccine-induced clotting, which could risk missing or delaying diagnoses. As our understanding of this novel condition evolves, heightening our clinical awareness can improve outcomes for patients through early testing and treatment,” she commented.

Details of these findings are published in the British Journal of Haematology.