Identifying life-threatening VITT using a highly specific ELISA

As vaccine-induced immune thrombocytopenia and thrombosis (VITT) is a new condition, there is limited evidence available to inform clinical management. Recent research¹ by the UK’s Expert Haematology Panel indicates overall mortality to be as high as 22%, with the greatest risk of death from those presenting with both a low platelet count and an intracranial haemorrhage. Most were previously fit and healthy young people. The National Institute for Health and Care Excellence (NICE) has also adapted its own recent guidelines based on this haematology panel’s findings.² Fortunately, treatment options are available, with early interventions thought to produce the best outcomes.

            Vaccine-induced immune thrombocytopenia and thrombosis is primarily caused by the patient’s blood developing an antibody that cross reacts with platelet factor 4 and activates the platelets. However, this presents in a pathogenically similar way to heparin-induced thrombocytopenia (HIT), which is a common prothrombotic complication of unfractionated heparin (UFH) and low molecular weight heparin (LMWH) therapies. In a vaccinated patient, the symptoms have been seen to develop from five to 30 days after the first vaccine dose, further reflecting an immunological pattern like that of HIT.

            If the patient is not receiving heparin therapy, a warning sign would be a low platelet count, with low fibrinogen and disproportionally raised D-dimer. For vaccinated patients presenting with these symptoms, additional specialist investigation running an enzyme-linked immunosorbent assay (ELISA) such as Stago’s Asserachrom HPIA becomes necessary.³