On the likelihood of the individuals vaccinated with the adenoviral vector-based COVID-19 vaccines to develop vaccine-induced immune thrombotic thrombocytopenia being infected with adenovirus

Adenoviral vectors represent effective vaccine agents for various infectious diseases by eliciting a robust humoral and cellular immune response, which prompted their utilization during the COVID-19 pandemic. However, following vaccination with two adenoviral-based COVID-19 vaccines, Ad26.COV2.S (Janssen), and ChAdOx1 nCov-19 (AstraZeneca), abnormal and exceptional blood clotting conditions (Vaccine-Induced Thrombotic Thrombocytopenia, VITT) were reported, adding a warning to the use of these vaccines in controlling the pandemic about this clotting disorder. Secondary immune thrombocytopenia cases have also been discovered in individuals vaccinated with mRNA-based COVID-19 vaccines (Moderna and Pfizer). Remarkably, no such condition was observed with other SARS-CoV-2 vaccines, such as Ad5 nCov (Cansino), as well as with Ebola vaccines, which also utilize adenoviral vectors. Research from then on has focused on identifying the specific vaccine components involved in triggering this clotting syndrome. Among the explanations proposed, it was found that the clotting disorder caused by vaccination with adenoviral-based COVID-19 vaccines resembles heparin-induced thrombocytopenia and sporadic infection with adenovirus. This identified an important factor that may significantly affect the future of adenoviral vectors as vaccine agents if they induce such a fatal disorder. This hypothesis-driven article explores whether sporadic adenovirus infection could trigger VITT in individuals previously immunized with the Janssen or AstraZeneca vaccines.