Journal of Neurology | 2021
Vaccine-induced immune thrombosis and thrombocytopaenia: incidence, mechanism and treatment
Abstract
Development, testing, and licencing of vaccines against COVID19 has occurred at unprecedented speed. Four types of vaccine have been developed to date: mRNA vaccines (e.g. PfizerBioNTech, Moderna), viral vector DNA vaccines (e.g. OxfordAstraZeneca (OAZ), Johnson and Johnson-Janssen, CanSino, Gamalaya Sputnik), inactivated SARS-CoV2 viral proteins (e.g. Sinovac, Sinopharm) and subunit vaccines (e.g. EpiVacCorona, GSK-Sanofi). The emergence of rare significant side effects of vaccination is concerning and disappointing, but also highly probable given the scale of the vaccination programme in comparison with the size of the clinical trial cohorts. Vaccineinduced immune thrombosis and thrombocytopaenia (VITT) has become a well described rare consequence of vaccination with adenoviral vector SARS-CoV2 vaccines. This vaccine technology has been deployed previously, for example, in the 2018 Ebola outbreak, but in relatively small populations. In contrast, by July 2021, over 1 billion doses of the Oxford-AstraZeneca vaccine had been despatched to over 170 countries. VITT is characterised by venous or arterial thrombosis and thrombocytopaenia following vaccination against covid-19. It is also sometimes called vaccine-induced prothrombotic immune thrombocytopaenia (VIPIT) or thrombotic thrombocytopenic syndrome (TTS). Although incompletely defined, VITT appears to have a high mortality and morbidity and treatment guidelines are rapidly evolving. We review three papers for this month’s journal club that provide insights into the scale of the problem, the disease mechanism and treatment. COVID‐19 vaccine‐associated cerebral venous thrombosis in Germany