The COVID-19 vaccination rollout, especially in 2021, was largely a global success story. It was the largest public health exercise in history, and demonstrated how advancements in technology and medicine can avert disaster and save lives. 

The fine print on the COVID-19 vaccines is that adverse events may take place in a small number of individuals, a fact that was loudly broadcasted by organizations skeptical of vaccines. Unfortunately, the mention of a few cases of adverse events among hundreds of millions of individuals was likely to heavily skew public imagination and depress vaccination registration. 

Nevertheless, adverse events did occur, and it is only ethical that the medical community learn about them in order to, first of all, treat them, and second of all, to prevent them from occurring in the future. 

Abnormal Thrombosis Episodes Post-Vaccination 

In the Journal of Thrombosis and Hemostasis, Thaler and colleagues presented the case study of a patient who developed thrombosis and immune thrombocytopenia after receiving a COVID-19 vaccine dose. 

“In March 2021, cases of thrombosis, including thrombosis at unusual sites (cerebral vein thrombosis or splanchnic vein thrombosis), and thrombocytopenia were reported after vaccination with the ChAdOx1 nCOV-19 vaccine (AstraZeneca) in several countries,” they wrote. “The term ‘vaccine-induced prothrombotic immune thrombocytopenia’ (VIPIT) was coined to reflect this new phenomenon.” 

A 62-year-old female in good health received the ChAdOx1 nCOV-129 vaccine and developed flu-like symptoms the following day. These include a moderate headache, dizziness, and aches in her joints. 

Read more about immune thrombocytopenia etiology 

She decided to take 1g of paracetamol. She remained afebrile and stayed at home to rest. The following day, she described feeling better but decided to take 400 mg aspirin. On days 3 and 4, she felt completely recovered and on day 4 drove 100 miles by car to have a vacation at the lower Austrian alpine foothills. The following day, she went cross-country skiing. 

In the evening, she began to develop chills and had a temperature of 39.8oC. She took 400 mg aspirin once more. The following morning, she took 400 mg aspirin and was afebrile. She felt better and made the decision to drive back home. 

On days 7 and 8, she felt well enough to continue her work as a psychotherapist. However, on the evening of day 8, she accidentally bit her lip and developed a hematoma that was described as being unusually large. She also noticed bleeding at her gums, something she never experienced before. 

The next morning, she recognized a hematoma at her right ankle that was not precipitated by trauma. She then presented herself to the emergency ward of the Vienna General Hospital of the Medical University of Vienna. 

Upon history-taking, she revealed that she had substituted hypothyroidism of unresolved genesis since 20 years of age. She did not have any other relevant medical history, and she never underwent surgery. 

“Asking for bleedings prior to the current medical condition, she scored 0 in the [International Society of Thrombosis and Hemostasis] bleeding assessment tool,” the study authors wrote. 

Upon examination, she was afebrile, slightly hypertensive (blood pressure: 150/90), and had normal respiration and heart rates. Venous blood gas was normal, and a SARS-CoV-2 polymerase chain reaction test of a nasopharyngeal swab was negative. 

Her physicians did notice small hematomas and petechiae on her limbs. A quantitative rapid D-dimer test returned positive. An on-duty hematologist was consulted, and the patient was suspected of having VIPIT. 

A computed tomography scan (cerebral, chest, and abdominal) was performed but showed no pathologies. A hemogram revealed isolated thrombocytopenia; D-dimer was highly elevated, while fibrinogen was low. 

“The anti-platelet factor 4 (PF4)/heparin IgG enzyme-immunoassay, which has been recommended for VIPIT screening, was highly positive and supported the suspected diagnosis of VIPIT,” the authors of the study wrote. 

Her physicians substituted a low dose (1 g) of a fibrinogen concentrate on day 1 of hospitalization prior to [heparin-induced thrombocytopenia]-compatible anticoagulation with short-acting danaparoid-sodium. Anticoagulation with danaparoid was routinely monitored in order to obtain anti-Xa target trough levels of around 0.5 IU/mL. 

She was started on high dose intravenous immunoglobulin and prednisolone for 2 consecutive days. On day 4, her platelet count and fibrinogen levels returned back to normal and she was switched to oral apixaban 5 mg twice daily. 

On day 6, the patient was discharged. An outpatient visit 5 days later revealed her to be in good condition with normal laboratory values. 

Treating a New Syndrome 

The presentation of an adverse reaction to a newly developed vaccine is a predicament that many physicians would be happy to avoid, since there are so many uncertainties involved and miscalculations can have grave consequences. 

Read more about immune thrombocytopenia treatment 

The patient in this case study developed a mild case of thrombosis and thrombocytopenia that resolved readily after a few days of treatment. However, it should be noted that moderate-to-severe thrombocytopenia/thrombotic complications post-vaccination have been reported in medical literature. In many of these cases, the thrombosis was detected in the cerebral veins, with splanchnic vein thrombosis or pulmonary embolism also being present. 

“The [vaccine-associated immune thrombosis and thrombocytopenia] syndrome is a very rare but often life-threatening thrombotic condition associated with ChAdOx1 nCoV-19 vaccine,” Franchini and colleagues wrote in the European Journal of Hematology. “Additional research is also required to identify, if possible, those individuals at increased risk of developing [this] syndrome in order to prevent this fearsome complication.” 


Thaler J, Ay C, Gleixner KV, et al. Successful treatment of vaccine-induced prothrombotic immune thrombocytopenia (VIPIT)J Thromb Haemost. Published online June 11, 2021. doi:10.1111/jth.15346

Franchini M, Liumbruno GM, Pezzo M. COVID-19 vaccine-associated immune thrombosis and thrombocytopenia (VITT): diagnostic and therapeutic recommendations for a new syndromeEur J Haematol. Published online May 13, 2021. doi:10.1111/ejh.13665