Review and evolution of guidelines for diagnosis of COVID-19 vaccine induced thrombotic thrombocytopenia (VITT)

Clin Chem Lab Med. 2021 Nov 1;60(1):7-17. doi: 10.1515/cclm-2021-1039. Print 2022 Jan 26.


Coronavirus disease 2019 (COVID-19) is a life-threatening infectious disease caused by Severe acute respiratory syndrome Coronavirus-2 (SARS-CoV-2). In response to the still ongoing pandemic outbreak, a number of COVID-19 vaccines have been quickly developed and deployed. Although minor adverse events, either local (e.g., soreness, itch, redness) or systematic (fever, malaise, headache, etc.), are not uncommon following any COVID-19 vaccination, one rare vaccine-associated event can cause fatal consequences due to development of antibodies against platelet factor 4 (PF4), which trigger platelet activation, aggregation, and possible resultant thrombosis, often at unusual vascular sites. Termed thrombosis with thrombocytopenia syndrome (TTS) by reporting government agencies, the term vaccine-induced (immune) thrombotic thrombocytopenia (VITT) is more widely adopted by workers in the field. In response to increasing reports of VITT, several expert groups have formulated guidelines for diagnosis and/or management of VITT. Herein, we review some key guidelines related to diagnosis of VITT, and also provide some commentary on their development and evolution.

Keywords: diagnosis; guideline; laboratory testing; thrombosis with thrombocytopenia syndrome (TTS); vaccine induced thrombotic thrombocytopenia (VITT).

Publication types

  • Review

MeSH terms

  • COVID-19 / prevention & control
  • COVID-19 Vaccines / adverse effects*
  • Humans
  • Thrombocytopenia* / chemically induced
  • Thrombocytopenia* / diagnosis
  • Thrombosis* / chemically induced
  • Thrombosis* / diagnosis


  • COVID-19 Vaccines