Thrombocytopenia After Coronavirus Disease 2019 Vaccination: Remember to Put the Blame on Others Too

Thrombosis and thrombocytopenia in COVID-19 and after COVID-19 vaccination

“…Nevertheless, the differential diagnosis of SLE from VITT/TTS should be considered. Recently, a rare case of newly developed SLE with thrombosis and thrombocytopenia was reported [70] . Although the low sensitivity of the rapid test for anti-PF4 antibody in VITT/TTS has already been known, one should also take into account the potential risk of false-positive reactions of the rapid test and ELISA anti-PF4 antibody (e.g., cross-reacting antibodies and subjective interpretation of the test result).…”

The authors reply

“…In summary, when patients develop thrombosis with thrombocytopenia after COVID-19 vaccination, ELISA (rather than rapid immunoassay) testing for anti-PF4 antibodies is appropriate for screening of VITT, but even when positive results are obtained, a definitive diagnosis should be made based on positive test results in a suitable platelet activation assay. The intriguing case reported by De Bruyne et al (1) suggests that on rare occasions vaccination might trigger or exacerbate SLE with APS.…”

“…The authors reply: W e appreciate De Bruyne et al (1) for presenting an interesting and informative case, initially suspected to be vaccine-induced thrombotic thrombocytopenia (VITT). Diagnostic suspicion of VITT is of course appropriate when a patient presents with thrombosis and thrombocytopenia 5 days after AstraZeneca/Oxford (ChAdOx1 nCoV-19) vaccination.…”

“…Indeed, the patient’s clinical and laboratory findings are consistent with VITT based on a recent summary of 220 VITT cases (2). The pitfall in the case reported by De Bruyne et al (1) was the “positive” rapid test for heparin-induced thrombocytopenia (HIT) performed using the STic Expert HIT kit (Diagnostica Stago, Asnieres, France), which uses lateral flow technology to detect IgG against platelet factor 4 (PF4)/polyanion complexes; as De Bruyne et al (1) acknowledge, rapid PF4-dependent assays for VITT are usually negative. Indeed, in the case described, the enzyme-linked immunosorbent assay (ELISA) was negative, indicating the STic Expert HIT assay was likely a false-positive test.…”