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Vaccine induced immune thrombocytopenia and thrombosis: summary of NICE guidance

BMJ 2021; 375 doi: (Published 01 October 2021) Cite this as: BMJ 2021;375:n2195

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Re: Vaccine induced immune thrombocytopenia and thrombosis: summary of NICE guidance

Dear Editor
We thank the author, Dr. Kareem I. Batarseh, for the interesting comment that VITT has been seen before. We appreciate the author informing us of a paper by Lozier et al where Rhesus macaques received an adenoviral vector and Factor IX cassette and developed a coagulopathy. There was also a hepatitic response and very high levels of interleukin -6 accompanied by prolongation of PTT/PT, very high levels of fibrinogen and a fall in platelet count. This is not the picture of VITT. Indeed when reviewing the 5 criteria of VITT, there was 1) no thrombosis; 2) timing was not in keeping with an immune response because changes happened in the first few days rather than after day 5 as we see with VITT; 3) elevation of fibrinogen was seen rather than a fall as seen in VITT and lastly no evidence that this process was mediated by anti- platelet factor 4 antibodies, which is characteristic of VITT.

We are aware that an adenoviral vector has been used for the EBOLA vaccine and while no cases of VITT have been described after this vaccine, it is possible that post vaccine surveillance did not have the granularity to detect VITT cases. For the moment at least, VITT is unique to occurring after COVID-19 vaccines.

Competing interests: No competing interests

15 October 2021
Justine Karpusheff
Associate Director
Beverley Hunt, Sue Pavord, Susan Bewley, Daniel Horner