Τι είναι το (VIPIT) Vaccine-Induced Prothrombotic Immune Thrombocytopenia παρενέργεια της Astra Zeneca και όχι μόνο

Interim Guidelines: Diagnosis and Management of VaccineInduced Prothrombotic Immune Thrombocytopenia (VIPIT) following AstraZeneca COVID19 Vaccinations12April 2021
IntroductionRare cases of blood clots with low platelets after receipt ofAstraZeneca(AZ)COVID19 vaccine have been reported.At present there is no clear signal of risk factorsfor this condition.This document provides guidance to UN medical staffglobally on the diagnosis, management and reportingof vaccineinduced prothrombotic immune thrombocytopenia (VIPIT)cases.
UN medical staff need to be alert for this syndrome andarrange for early referral tolocal hospitalsor haematologistsand/orconsider early medical evacuation for further lab confirmation and treatment of this condition.
For any questions, contact DHMOSH Public Health atdosdhmoshpublichealth@un.org
Note that this is a living document which will be updated as more information emerges. Current Situation Update At the time of writing, the AstraZeneca vaccine is currently being authorized for use in the EU and several other countries, including the UK, Canada and India. Based on a multinational Phase 3 trial, the vaccine had 70.4% efficacy in preventing symptomatic COVID19 at/after 14 days post second dose.  
Although there is some concern about vaccine efficacy against certain “variants”, the WHO continues to recommend use of this vaccine even if those variants are circulating in a country1,2.
Vaccine induced prothrombotic immune thrombocytopenia,or VIPIT,is acondition of blood clots associated with low platelet counts, that occurs following receipt of the vaccine. The likely mechanism is antibodies that induce massive platelet activation, reducing platelet count and causing thrombosis although the full mechanism remains to be elucidated.
This syndrome is thought to mimic heparininduced thrombocytopenia(HIT) but does not require heparin itself as a trigger. Most cases occurred 5 to 28days 3after receipt of the AZ vaccine, and in women 4 under 60 years old5.Available evidence so far, at the time of writing, continues to suggest that this syndrome is extremely rare6 though information continues to evolve.Because of the rarity of events and potential severity of COVID19, the European Medicines Agency (EMA) concluded that the overall benefits of the vaccine continue to outweigh the risk.
The WHO has also stated that the very rare incidence should be weighed against the risk of morbidity from COVID1https://www.who.int/newsroom/featurestories/detail/theeffectsofvirusvariantsoncovid19vaccines2 AstraZeneca ChAdOx1S/nCoV19 [recombinant], COVID19 vaccine (who.int)3https://bsh.org.uk/media/19530/guidanceversion13onmngmtofthrombosiswiththrombocytopeniaoccurringafterc19vaccine_20210407.pdf4
Note that additional studies needed on this since many vaccine recipients are women as they fall under the high priority first responders groups such as teachers and healthcare workers being prioritized early for vaccination.5https://www.ema.europa.eu/en/news/astrazenecascovid19vaccineemafindspossiblelinkveryrarecasesunusualbloodclotslowblood6 At the time of writing, Norway has reported a rate of 1 in every 25,000 doses, Germany reported 1 in 100,000 doses, while Europe’s overall figures are 1 in 210,000. The UK has reported about 1 in 500,000 doses. Specifically, 169 reported cases of cerebral venous sinus thrombosis (CVST) and 53 cases of splanchnic vein thrombosis were reported in 34 million vaccine recipients in the UK and European Economic Areaas of time of writing this document.

COVID19 VACCINESVIPIT INTERIM GUIDANCE 12APRIL 2021 219. See WHO statement here. The WHO has stated that a causal relationship, while plausible, has still yet to be confirmed.Clinical Presentation of VIPITPatients with VIPIT may present with cerebral sinus vein thrombosis (CSVT), or with other arterial or venous clots. Symptoms that make you suspect VIPIT include:persistent and severe headache focal neurological symptomsseizures, or blurred or double vision (suggesting CSVT or arterial stroke)shortness of breath or chest pain (suggesting pulmonary embolism or acute coronary syndrome)abdominal pain (suggesting portal vein thrombosis) or limb swelling, redness, pallor, or coldness (suggesting deep vein thrombosis or acute limb ischemia).

VIPIT cases usually present 5 to 28 days7after vaccination, so the above symptoms occurring within this time frame should raise clinical suspicion of VIPIT.What To Do WhenAn Individual Presents with the Above Symptoms1.Ask patient about their COVID19 vaccine history and note the date that they received the doses, if any2. Draw a complete blood count (CBC)from the patient3.If platelet count is equal or less than150 x 109/L, ANDtheir symptoms occur within 28 days after COVID19 vaccination, such patientsare considered a suspect case of VIPIT.4. Suspect VIPIT patients need to be further evaluated for VIPIT through Ddimer and fibrinogen levels, blood films drawn to confirm thrombocytopenia,PF4 antibody assay (ELISA HIT assay),and imaging(e.g. CT or MRI) to rule out in particular CSVT.a. Cases are often characterized also with very raised D Dimerlevels(>4000 mcg/L)above the level expected for VTE and many develop low fibrinogen levels.b. Antibodies to platelet factor 4 (PF4), as detected by ELISA HeparinInduced Thrombocytopenia (HIT) assay,have also been identified in this syndrome.5.

If such lab tests and services in #4 are not available in your clinic, you need to organize areferral to a local hospitalwith theseservices, or medically evacuateto rule out and/or treat VIPIT. A summary of these steps isfoundin Annex 1.Treatment of VIPITTreatment of suspect or confirmed VIPIT requires consultation with a specialist hematologist. However, pleasebear in mind the following principles for treating such patients:1.DO NOT giveheparin7https://bsh.org.uk/media/19530/guidanceversion13onmngmtofthrombosiswiththrombocytopeniaoccurringafterc19vaccine_20210407.pdf

COVID19 VACCINESVIPIT INTERIM GUIDANCE 12APRIL 2021 32.Avoidplatelettransfusions3.Consult a hematologist (in person, virtually, by phone)4.Give intravenous immunoglobulin 1 g/kg daily for 2 days for severe or lifethreatening clots,if available.Further IVIG may require balancing bleeding and thrombotic ris5.Use first line anticoagulants: direct oral antiXa inhibitors (e.g. rivaroxaban, apixaban, edoxaban)

Until VIPIT has been ruled out, anticoagulation with heparin (both unfractionated heparin and low molecular weight heparins) should not be given. Platelet transfusionsshould not be given. Further information concerning specialized guidance on how to confirm VIPITdiagnosis and its clinical management is available at UK: Guidance Produced from the Expert Haematology Panel (EHP) focused on Covid19 Vaccine induced Thrombosis and Thrombocytopenia (VITT)Treatment of VIPIT

With Life Threatening Blood ClotsIn patients with confirmed VIPIT and severe or lifethreatening blood clots (e.g., CSVT, splanchnic vein thrombosis), it is important to administer high doseintravenous immunoglobulin (IVIG)at 1g/kg of body weight daily for two daysurgently, if available.This treatment should beguided by a consulting hematologistand can be given whilst awaiting confirmatory diagnosis.Reporting VIPITPrompt reportingof such cases amongst UN personnel is essential to learn more about this rare but serious thrombotic phenomenon.

All cases of thrombosis, thrombocytopenia occurring within 28 days of COVID19 vaccine must be reported immediately toDHMOSH Public Health atdosdhmoshpublichealth@un.orgReferencesUK: GuidanceProduced from the Expert Haematology Panel (EHP) focused on Covid19 Vaccine induced Thrombosis and Thrombocytopenia (VITT)Ontario: VaccineInduced Prothrombotic Immune Thrombocytopenia (VIPIT) Following AstraZeneca COVID19 VaccinationInterim statement of the COVID19 subcommittee of the WHO Global Advisory Committee on Vaccine Safety on AstraZeneca COVID19 vaccinehttps://www.ema.europa.eu/en/news/astrazenecascovid19vaccineemafindspossiblelinkveryrarecasesunusualbloodclotslowbloodNEJM: Thrombosis and Thrombocytopenia after ChAdOx1 nCoV19 Vaccination (9 April 2021)

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