Severe fever with thrombocytopenia syndrome (SFTS), a tickborne viral disease, has been identified in China, South Korea, and Japan since 2009. We found retrospective evidence of SFTS virus (SFTSV) ...infection in Vietnam, which suggests that SFTSV infections also occur in Vietnam, where the virus has not been known to be endemic.
Background
Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), which causes novel coronavirus disease 2019 (COVID‐19), is spreading rapidly around the world. Thrombocytopenia in patients ...with COVID‐19 has not been fully studied.
Objective
To describe thrombocytopenia in patients with COVID‐19.
Methods
For each of 1476 consecutive patients with COVID‐19 from Jinyintan Hospital, Wuhan, China, nadir platelet count during hospitalization was retrospectively collected and categorized into (0, 50, (50, 100, (100‐150, or (150‐) groups after taking the unit (×109/L) away from the report of nadir platelet count. Nadir platelet counts and in‐hospital mortality were analyzed.
Results
Among all patients, 238 (16.1%) patients were deceased and 306 (20.7%) had thrombocytopenia. Compared with survivors, non‐survivors were older, were more likely to have thrombocytopenia, and had lower nadir platelet counts. The in‐hospital mortality was 92.1%, 61.2%, 17.5%, and 4.7% for (0, 50, (50, 100, (100‐150, and (150‐) groups, respectively. With (150‐) as the reference, nadir platelet counts of (100‐150, (50, 100, and (0, 50 groups had a relative risk of 3.42 (95% confidence interval CI 2.36‐4.96), 9.99 (95% CI 7.16‐13.94), and 13.68 (95% CI 9.89‐18.92), respectively.
Conclusions
Thrombocytopenia is common in patients with COVID‐19, and it is associated with increased risk of in‐hospital mortality. The lower the platelet count, the higher the mortality becomes.
Severe Fever with Thrombocytopenia Syndrome (SFTS) is an emerging infectious disease caused by a novel bunyavirus, SFTS virus (SFTSV), with fatal outcome developed in approximately 17% of the cases. ...Thrombocytopenia is a hallmark feature of SFTS, and associated with a higher risk of fatal outcome, however, the pathophysiological involvement of platelet in the clinical outcome of SFTS remained under-investigated. In the current study, by retrospectively analyzing 1538 confirmed SFTS patients, we observed that thrombocytopenia was associated with enhanced activation of the cytokine network and the vascular endothelium, also with a disturbed coagulation response. The platelet phenotypes were also extensively altered in the process of thrombocytopenia development of SFTS patients. More importantly, all these disturbed host responses were related to the severity of thrombocytopenia, thus were considered to play in a synergistic way to influence the disease outcome. Moreover, the clinical effect of platelet transfusion was assessed by comparing two groups of patients with or without receiving this therapy. As a result, we observed no therapy effect in altering frequencies of fatal outcome, clinical bleeding development, or dynamic change of platelet count during the hospitalization. It's suggested that platelet supplementation alone acted a minor role in improving disease outcome, therefore new therapeutic intervention to regulate host response should be proposed. The current results revealed some evidence of interrelationship between platelet count and clinical outcome of SFTS disease from the perspective of activation of the cytokine network, the vascular endothelium, and the coagulation/fibrinolysis system. These evaluations might help to attain a better understanding of the pathogenesis and therapy choice in SFTS.
Vaccine‐induced immune thrombotic thrombocytopenia (VITT) is a rare but severe immunological reaction to the non‐replicable adenoviral vector‐based COVID‐19 vaccines. Extreme activation of platelets ...and the coagulation system leads to a high risk of death from venous or arterial thrombosis or secondary hemorrhage. Public and clinician awareness has reduced mortality of VITT by nearly 90%. The World Health Organization provided a guideline in July 2021 on diagnosis and management of VITT (also called thrombosis with thrombocytopenia syndrome, or TTS). Since July 2021, new, clinically relevant information has become available. This update has been summarized by the authors in an informal process with recommendations for low resource environments. We provide new available evidence on VITT to empower clinicians to recognize VITT early, then effectively diagnose and treat the disorder to reduce morbidity and mortality. We strongly encourage production of clear management pathways for primary care settings and hospital settings.
Current vaccines for the Coronavirus Disease of 2019 (COVID-19) have demonstrated efficacy with low risk of adverse events. However, recent reports of thrombosis with thrombocytopenia syndrome (TTS) ...associated with adenovirus vector vaccines have raised concern.
This narrative review summarizes the current background, evaluation, and management of TTS for emergency clinicians.
TTS, also known as vaccine-induced immune thrombotic thrombocytopenia, is a reaction associated with exposure to the ChAdOx1 nCoV-19 (Oxford-AstraZeneca) and AD26.COV2·S (Johnson & Johnson) vaccine, which may result in thrombocytopenia and thrombotic events. There are several case series of patients diagnosed with TTS, but the overall incidence is rare. TTS is characterized by exposure to one of the aforementioned vaccines 4–30 days prior to presentation, followed by thrombosis, mild-to-severe thrombocytopenia, and a positive platelet factor-4 (PF4)-heparin enzyme-linked immunosorbent assay (ELISA). Thrombosis typically involves atypical locations, including cerebral venous thrombosis and splanchnic vein thrombosis. Evaluation should include complete blood count, peripheral smear, D-dimer, fibrinogen, coagulation panel, renal and liver function, and electrolytes, as well as PF4-heparin ELISA if available. Consultation with hematology is recommended if suspected or confirmed. Treatment may include intravenous immunoglobulin and anticoagulation, while avoiding heparin-based agents and platelet transfusion.
With increasing vaccine distribution, it is essential for emergency clinicians to be aware of the evaluation and management of this condition.
Corona Virus Disease 2019 (COVID-19) is caused by the novel coronavirus SARS-CoV-2. Emerging genetic and clinical evidence suggests similarities between COVID-19 patients and those with severe acute ...respiratory syndrome and Middle East respiratory syndrome. Hematological changes such as lymphopenia and thrombocytopenia are not rare in COVID-19 patients, and a smaller population of these patients had leukopenia. Thrombocytopenia was detected in 5–41.7% of the patients with COVID-19. Analyzing the dynamic decrease in platelet counts may be useful in the prognosis of patients with COVID-19. However, the mechanisms underlying the development of thrombocytopenia remain to be elucidated. This review summarizes the hematological changes in patients infected with SARS-CoV-2 and possible underlying mechanisms of thrombocytopenia development.
•Early diagnosis and treatment of COVID-19 patients can reduce mortality.•There is no laboratory test index to predict disease progression and prognosis.•Progressive decline in platelets may be a prognostic factor for COVID-19 patients.•Monitoring platelet count may be an effective index for COVID-19 progression.
COVID‐19 (coronavirus disease 2019) represents a pandemic, and several vaccines have been produced to prevent infection and/or severe sequelae associated with SARS‐CoV‐2 (severe acute respiratory ...syndrome coronavirus 2) infection. There have been several reports of infrequent post vaccine associated thrombotic events, in particular for adenovirus‐based vaccines. These have variously been termed VIPIT (vaccine‐induced prothrombotic immune thrombocytopenia), VITT (vaccine‐induced immune thrombotic thrombocytopenia), VATT (vaccine‐associated immune thrombotic thrombocytopenia), and TTS (thrombosis with thrombocytopenia syndrome). In this report, the laboratory test processes, as utilised to assess suspected VITT, are reviewed. In published reports to date, there are notable similarities and divergences in testing approaches, potentially leading to identification of slightly disparate patient cohorts. The key to appropriate identification/exclusion of VITT, and potential differentiation from heparin‐induced thrombocytopenia with thrombosis (HITT), is identification of potentially differential test patterns. In summary, testing typically comprises platelet counts, D‐dimer, fibrinogen, and various immunological and functional assays for platelet factor 4 (PF4) antibodies. In suspected VITT, there is a generally highly elevated level of D‐dimer, thrombocytopenia, and PF4 antibodies can be identified by ELISA‐based assays, but not by other immunological assays typically positive in HITT. In addition, in some functional platelet activation assays, standard doses of heparin have been identified to inhibit activation in suspected VITT, but they tend to augment activation in HITT. Conversely, it is also important to not over‐diagnose VITT, given that not all cases of thrombosis post vaccination will have an immune basis and not all PF4‐ELISA positive patients will be VITT.
Essentials
Many patients produce antibodies but few lead to heparin‐induced thrombocytopenia (HIT).
Pathogenic epitopes are difficult to identify as HIT antibodies are polyclonal and polyspecific.
...KKO binding to platelet factor 4 (PF4) depends on 13 amino acids, three of which are newly observed.
Five amino acids in PF4 can help distinguish pathogenic from non‐pathogenic antibodies.
Summary
Background
Heparin‐induced thrombocytopenia (HIT) is an adverse drug reaction that results in thrombocytopenia and, in some patients, thrombotic complications. HIT is mediated by antibodies that bind to complexes of platelet factor 4 (PF4) and heparin. The antigenic epitopes of these anti‐PF4/heparin antibodies have not yet been precisely defined, because of the polyspecific immune response that characterizes HIT.
Objectives
To identify PF4 amino acids essential for binding pathogenic HIT antibodies.
Methods
Alanine scanning mutagenesis was utilized to produce 70 single point mutations of PF4. Each PF4 mutant was used in an enzyme immunoassay (EIA) to test their capacity to bind a platelet‐activating murine monoclonal anti‐PF4/heparin antibody (KKO) and HIT patient sera (n = 9).
Results and Conclusions
We identified 13 amino acids that were essential for binding KKO because they directly affected either the binding site or the antigenic conformation of PF4. We also identified 10 amino acids that were required for the binding of HIT patient sera and five of these amino acids were required for binding both KKO and the HIT patient sera. The 10 amino acids required for binding HIT sera were further tested to differentiate pathogenic HIT antibodies (platelet activating, n = 45) and non‐pathogenic antibodies (EIA‐positive but not platelet activating, n = 28). We identified five mutations of PF4 that were recognized to be essential for binding pathogenic HIT antibodies. Using alanine scanning mutagenesis, we characterized possible binding sites of pathogenic HIT antibodies on PF4.
Severe fever with thrombocytopenia syndrome (SFTS) is an acute febrile illness characterized by fever, leukopenia, thrombocytopenia, and gastrointestinal symptoms such as diarrhea, nausea, and ...vomiting resulting from infection with the SFTS virus (SFTSV). The SFTSV is transmitted to humans by tick bites, primarily from
,
, and
. Human-to-human transmission has also been reported. Since the first report of an SFTS patient in China, the number of patients has also been increasing. The mortality rate of patients with SFTS remains high because the disease can quickly lead to death through multiple organ failure. In particular, an average fatality rate of approximately 20% has been reported for SFTS patients, and no treatment strategy has been established. Therefore, effective antiviral agents and vaccines are required. Here, we aim to review the epidemiology, clinical manifestations, laboratory diagnosis, and various specific treatments (i.e., antiviral agents, steroids, intravenous immunoglobulin, and plasma exchange) that have been tested to help to cope with the disease.
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