“…49 A small case series of 20 patients with a prior history of heparin-induced thrombocytopenia tolerated the AstraZeneca ChAdOx COVID-19 adenoviral vector vaccine. 50 Myocarditis has been reported primarily after the second dose of the mRNA vaccines and more prevalently in men less than 30 years of age. [51][52][53] One study of interest suggested that this might be more common with the traditional 3-or 4-week interval between mRNA vaccines vs the extended 12-to 16-week interval in the rollout in Canada.…”
“…49 A small case series of 20 patients with a prior history of heparin-induced thrombocytopenia tolerated the AstraZeneca ChAdOx COVID-19 adenoviral vector vaccine. 50 Myocarditis has been reported primarily after the second dose of the mRNA vaccines and more prevalently in men less than 30 years of age. [51][52][53] One study of interest suggested that this might be more common with the traditional 3-or 4-week interval between mRNA vaccines vs the extended 12-to 16-week interval in the rollout in Canada.…”
“…Although, patients with a history of Heparin Induced Thrombocytopenia (HIT) are considered at an increased risk for symptomatic VITT, this is not a data driven conclusion and in the United Kingdom, 20 of 60 patients with a confirmed history of HIT received the CHaDOx1 nCov-19 AstraZeneca vaccination with none reporting any features suggestive of VITT [18]. Regardless, the authors continued an initiative to guide patients with a history of HIT away from use the AstraZeneca vaccine.…”
Section: Thrombosis With Thrombocy-topenia Syndrome (Tts)mentioning
This review includes data supporting thrombocytopenia as an emerging adverse event associated with SARS-CoV2 vaccination, analyzes the published case reports supporting an association with acquired Thrombotic Thrombocytopenic Purpura (aTTP), reviews the association of Thrombosis with Thrombocytopenia Syndrome (TTS) and Immune Thrombocytopenia Purpura (ITP), analyzes data from the U.S. Food and Drug Administration’s (FDA) Vaccine Adverse Event Reporting System (VAERS) database, provides guidance for clinicians caring for patients desiring vaccination but at potential risk of COVID-19 vaccination associated thrombocytopenia, and provides guidance for patients with a history of thrombocytopenia to better enable an informed decision regarding the choice of vaccination. Although the incidence of thrombocytopenia is sufficiently low to allow the continued use of SARS-CoV2 vaccines in patients with a history of thrombocytopenia, caution is advised. The burden of disease in reported patients was significant with death in 8.99% of patients developing thrombocytopenia after receiving the COVID-19 vaccine and 15.4% having a life-threatening event. The burden on the healthcare system includes 30.6% of reported patients developing thrombocytopenia after receiving the COVID-19 vaccine requiring an ED visit, 26.5% requiring an office visit, and 49.5% requiring hospitalization. Hospitalizations were significant with a median stay of 7.21 days. Patients desiring vaccination should be screened for prior thrombocytopenia and counseled on the risks/benefits of vaccination that are unique to their medical history. Patients with a history of thrombocytopenia may choose to receive vaccination but should be monitored for the development of thrombocytopenia during 0-90 days and possibly as long as nine months following their last dose of vaccination.
“…Supporting the above is the fact that adenoviruses are known to directly interact with PF4 and cause platelet aggregation [ 55 , 56 ]. It is important to mention that no confirmative evidence exist so far, regarding enhanced risks of VITT syndrome in patients with prior history of HIT [ 57 , 58 ]. Fig.…”
COVID-19 is an infectious disease caused by a single-stranded RNA (ssRNA) virus, known as SARS-CoV-2. The disease, since its first outbreak in Wuhan, China, in December 2019, has led to a global pandemic. The pharmaceutical industry has developed several vaccines, of different vector technologies, against the virus. Of note, among these vaccines, seven have been fully approved by WHO. However, despite the benefits of COVID-19 vaccination, some rare adverse effects have been reported and have been associated with the use of the vaccines developed against SARS-CoV-2, especially those based on mRNA and non-replicating viral vector technology. Rare adverse events reported include allergic and anaphylactic reactions, thrombosis and thrombocytopenia, myocarditis, Bell’s palsy, transient myelitis, Guillen-Barre syndrome, recurrences of herpes-zoster, autoimmunity flares, epilepsy, and tachycardia. In this review, we discuss the potential molecular mechanisms leading to these rare adverse events of interest and we also attempt an association with the various vaccine components and platforms. A better understanding of the underlying mechanisms, according to which the vaccines cause side effects, in conjunction with the identification of the vaccine components and/or platforms that are responsible for these reactions, in terms of pharmacovigilance, could probably enable the improvement of future vaccines against COVID-19 and/or even other pathological conditions.
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