ABSTRACT
Background: The majority of adverse reactions (ARs) induced by COVID-19 vaccines were considered as mild-to- moderate reactogenicity events. but, despite the well proven efficacy and the safety of COVID-19 vaccines, some serious adverse have been emerging including neurological and thromboembolic complications (TEC) that are rare but life-threatening Method: we had included all patients with thromboembolic complications following COVID-19 vaccines notified the department of pharmacovigilance of the university hospital of Monastir Results: From total of 339 ADRs related to COVID-19 vaccination, 8 patients had TEC (two females and 6 males with median age of 68 years (31 -82 and)). The most common thromboembolic adverse events were ischemic cerebral stroke (62.5%) and deep vein thrombosis (37.5%). Medium time to the onset of TEC was 13.3 days (1-30 days). TEC were associated with the first dose of vaccine. Related vaccines with TEC were COMIRNATY (Pfizer/BioNTech) in 6 cases and Vaxzevria (Oxford/ AstraZeneca) in 2 cases. All patients were hospitalised. Seven patients had recovered with two of them having motor deficit sequelae while one patient had a fatal evolution. Vaccine's imputability was probable in four cases taking into consideration the clear temporal relationship between their administration and the onset of symptoms and the exclusion of other alternative causes after exhaustive investigations. However, three patients had predisposing factors for thrombosis and the imputability of the vaccines were uncertain. Since the gravity of these ARs, the second dose of the related vaccine was contraindicated. An inactivated COVID-19 vaccine were recommended as an alternative to the second dose of vaccination. Conclusion(s): In literature, reports of TEC had been increasingly described with mRNA and adenoviral vaccines with unproven causality. Vaccine's benefits outweigh the risk of any adverse complications associated with its use. As causal association is still controversial, further study is, however, necessary to better prove it.