Table 1.

Clinical and laboratory features of three patients

Characteristics	Patient 1	Patient 2	Patient 3
Age (years)	61	53	55
Sex	Female	Female	Male
Comorbid conditions	Asthma, hypertension, high body mass index	Fibromyalgia	Nil
Time from vaccination to admission (days)	16	14	10
Medication on admission	Hormone replacement therapy, indapamide	None	None
Presenting symptoms	Shortness of breath, pain and swelling in the right leg	Headaches, facial weakness, hemiparesis	Headaches, dysphasia, right arm weakness
Site of thrombosis	Right main pulmonary artery extending into upper, middle and lower pulmonary arteries and left segmental pulmonary arteries	Superior sagittal sinus, right sigmoid, right transverse sinus	Cortical veins, superior sagittal sinus, left transverse, left sigmoid sinus and left internal jugular vein
Platelet count nadir (×10⁹/L (reference range 150–450))	25	24	21
D-dimer peak (ng/mL (reference range 0–350))	9376	5620	47 881
PT INR peak (normal range 0.80–1.20)	1.0	1.2	1.1
aPTTR peak (normal range 0.80–1.17)	1.1	0.9	0.97
Fibrinogen (Clauss) nadir (g/L (reference range 1.9–4.8))	1.26	1.90	1.33
SARS-CoV-2 PCR test result	Not detected	Not detected	Not detected
Rapid particle gel immunoassay	Weak positive	Negative	Negative
PF4-ELISA (optical density (cut-off for positive reaction >0.400))	2.871	2.631	2.423
Platelet functional assay	Positive	Negative	Negative
Anticoagulation therapy	Initial split dose of LMWH then fondaparinux	Nil	Alteplase
Platelet transfusion	1 unit	Multiple	Multiple
Other treatment	IVIG (1 g/kg) Dexamethasone (20 mg once daily for 4 days)	None	Dexamethasone 20 mg Cryoprecipitate
Outcome	Full recovery	Death	Death

aPTT, activated partial thromboplastin time; IVIG, intravenous immunoglobulin; LMWH, low molecular-weight heparin; PF4, platelet factor 4; PT INR, prothrombin time international normalised ratio.