Cerebral Coagulation Complications Following COVID-19 Adenoviral Vector Vaccines: A Systematic Review

Emergence of the novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak identified in late 2019 in Wuhan, China, was declared a pandemic in March 2020. High fatality rate in afflicted patients prompted scientists and physicians to develop various vaccines against the virus. While administration of millions of doses of the adenoviral vector vaccines (e.g., Oxford-AstraZeneca (ChAdOx1 nCoV-19) and Janssen/Johnson & Johnson (Ad26.COV2. S)) has helped control the disease, numerous cases of cerebral venous sinus thrombosis (CVST) with thrombocytopenia have been reported in vaccinated individuals. In this article, we aim to review the cases reported thus far and further discuss the association between the vaccine administration and subsequent cerebral thromboembolic events. Our study was performed and reported based on the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). PubMed, Google Scholar and Norris Medical Library databases were searched using the following terms: coronavirus disease 2019 (COVID-19) vaccines (“AstraZeneca” or “AZD1222 COVID vaccine” or “ChAdOx1 nCoV-19 COVID-19 vaccine” or “Janssen” or “Johnson & Johnson COVID vaccine” or “Ad26.COV2 COVID vaccine”), coagulopathy (“cerebral venous sinus thrombosis (CVST)” and “vaccine-induced immune thrombotic thrombocytopenia (VITT)” or “cerebral venous thrombosis (CVT)”) and thrombocytopenia. All the relevant studies within the English literature up to August 1, 2021, were included. Fourteen most recent articles reporting on 66 patients with CVST and VITT after adenoviral vector vaccination were reviewed by two independent authors. Age of the patients ranged from 18 to 60 years. The majority of cases were women (43 females versus 14 males). Platelet count was between 5 and 127 × 109/L. Above-normal D-dimer was found in 86% of the patients. A total of 68% of the patients had positive platelet factor 4 IgG assay in the absence of prior exposure to heparin. Among CVST cases following COVID vaccination, 44% succumbed to death. Early diagnosis and treatment of CVST plays a fundamental role in decreasing morbidity and mortality. Health care professional should be familiar with this rare complication post vaccination against COVID-19. Given the rarity of CVST after the COVID-19 vaccine, the benefit of vaccination outweighs the potential harm.