Interim Case Definition of Thrombosis with Thrombocytopenia Syndrome (TTS)

Since February 2021, multiple countries have reported cases of Thrombosis with Thrombocytopenia Syndrome (TTS) in persons who received the COVID-19 vaccine. To further our understanding of a possible association of cases observed with thrombocytopenia and thrombosis following receipt of COVID-19 vaccines, Brighton Collaboration has developed the following interim case definition. The purpose of this interim case definition is to identify individuals that could then be studied using a common study protocol and assessment.

Click here to view the current interim case definition November 11, 2021, v10.16.4.

Click here to view the previous interim case definition May 18, 2021, v10.16.3 please see p.3 for Explanatory Notes for this version.

Patients and healthcare professionals meeting this definition should report to their respective competent health authorities if they have not already. (e.g., for the EU, and the US).

We have compiled a master list of questions (and glossary of abbreviations) for the follow-up study of TTS patients here based on available questionnaires.  Please complete this questionnaire for TTS cases meeting the case definition and watch this space for instructions on how to share the data confidentially.

If you have any comments on the interim case definition, please submit them here.  Note that unless there is a strong reason to do so, we’ll postpone incorporating them until development of the final case definition.

More Case Definitions