Blood clots related to the AstraZeneca Covid-19 vaccine can be mitigated if detected early, new research shows.
Unusual blood clots with low blood platelets have been recognised as a very rare complication of the AstraZeneca vaccine. However, early testing for blood clots in patients who had received the vaccine led to them being treated successfully in a recent study.
The research comes after the National Immunisation Advisory Committee (Niac) said that AstraZeneca and Janssen (Johnson & Johnson) vaccines can be used for the under-40s.
The use of both vaccines is currently limited to the over-50s, but their use for younger groups could speed up the rollout amid the threat of the more highly transmissible Delta variant of Covid-19.
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Researchers from the Royal College of Surgeons Ireland (RCSI) and the National Coagulation Centre at St James’s Hospital say with increased awareness and clinical vigilance, patients can be diagnosed and quickly treated for potential clotting.
The researchers highlighted four patients who had clotting complications induced by the vaccine. Based on the current guidance, each patient could have been classified as a ‘low likelihood’ for this clotting when they presented to doctors, but all were sent for testing early, diagnosed and treated successfully.
"The risk of developing a blood clot from the vaccine is still far lower than the risk of developing clots from Covid-19, but it is imperative that clinicians are vigilant in detecting symptoms among vaccinated patients," said Dr Michelle Lavin, the lead author of the paper and researcher at the RCSI School of Pharmacy and Biomolecular Science.
Clinical awareness
The research has shown that current guidelines “lack the sensitivity to detect early cases of vaccine-induced clotting, which could risk missing or delaying diagnoses,” she said.
“As our understanding of this novel condition evolves, heightening our clinical awareness can improve outcomes for patients through early testing and treatment.”
Separately, consultant haematologist Dr Michelle Lavin warned that the “serious and sinister” side effects of Covid are much more alarming than the rare side effects of vaccines.
Speaking on RTÉ radio’s Morning Ireland, Dr Lavin welcomed Nphet’s reassessment of the age group that can use AstraZeneca.
Increased media awareness had helped people to get treated, she added. “Far more” patients in her research were concerned about symptoms than those diagnosed. “That’s always a good thing. We’re highlighting the value of early testing,” she said.
“This is an extremely rare condition, it looks like it is one in 80,000 vaccinations, so while it is a serious side effect, it is very infrequent.”
“We know the benefits of vaccination and the very serious side effects of getting Covid, there seems to be some sort of perception in the community that younger people aren’t affected by Covid.”
It was particularly important that people were protected against “very serious and sinister” affects of Covid, such as long Covid, and other complications.