TABLE 1.

Comparison between COVID‐19 and VITT

	VITT	COVID−19
Presentation	Acute condition 4 to 28 days after receiving adenoviral COVID‐19 vaccine Stronger	Acute condition 2–14 days after exposure to SARS‐CoV2 infection Less strong
Platelet activation	Yes	Yes
Thrombosis	Yes Venous and arterial sites Commonly CVS, splanchnic vein thromboses Other sites: DVT, PE, internal jugular, portal, aorto‐iliac, ilio‐femoral veins Multiple organ thrombi in brain, lungs, and kidneys	Yes Venous and arterial sites
PF4 ELISA	Positive (all)	Some are positive
Thrombocytopenia	Almost all cases Usually severe but variable levels reported Acute	Not in all cases Variable levels Usually in severe disease Some patients have elevated count
D‐dimer	Markedly elevated	Markedly elevated in severe cases, ARDS, or those with poor prognosis
Fibrinogen	Reduced	Elevated early Reduced later in the disease
DIC	Has not been reported	Has been reported
Multiple organ failure	No	Yes
Heparin exposure	No Should be avoided	Yes Standard practice
IVIg use	Yes, first line of treatment	Not likely

Abbreviations: ARDS, acute respiratory distress syndrome; CVS, cerebral venous sinus; DIC, disseminated intravascular coagulation; DVT, deep vein thrombosis; IVIg, intravenous immunoglobulin G; PE, pulmonary embolism; PF4, platelet factor 4; VITT, vaccine‐induced immune thrombotic thrombocytopenia.