Neurological

Rare events of ITP related to the ChAdOx1 vaccine

HealthDay News – The ChAdOx1-COVID-19 vaccine is associated with a slightly increased risk of idiopathic thrombocytopenic purpura (ITP), according to a study published online in Nature Medicine on June 9.

Colin R. Simpson, Ph.D., of Victoria University of Wellington in New Zealand, and colleagues used a nested case-control study and a confirmatory self-controlled case series analysis (SCCS) to determine the association between exposure to first-dose vaccination ChAdOx1 or BNT162b2 as well as haematological and vascular side effects.

The researchers identified an association between ChAdOx1 vaccination and ITP zero to 27 days after vaccination (adjusted rate ratio [aRR], 5.77; 95 percent confidence interval [CI], 2.41 to 13.83), with an estimated incidence of 1.13 per 100,000 doses; In the SCCS analysis, this finding turned out to be unlikely due to bias (RR 1.98; 95 percent CI 1.29 to 3.02). An increased risk of arterial thromboembolic events was also observed zero to 27 days after vaccination (aRR 1.22; 95 percent CI 1.12 to 1.34) with an SCCS RR of 0.97 (95 percent KI 0.93 to 1.02). No positive associations with thrombocytopenic, thromboembolic or hemorrhagic events were observed for BNT162b2.

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“Reassuringly, we did not see an overall increased risk of ITP, clotting and bleeding in those who received the Pfizer BioNTech mRNA vaccine,” Simpson said in a statement. “We now plan to update our analysis as the vaccine program expands to younger, healthier people and new vaccines become available.”

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COVID19 COVID19 Vaccine General Neurology

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