![]() ![]() This FAQ is designed to provide an overview of considerations around the diagnosis and treatment of VITT. On the FDA modified the JJ vaccine EAU to limit administration only to those older than 18 years who are unable to receive any other vaccine due to anaphylaxis to mRNA vaccine components or unwillingness or inability to receive any other vaccine, grounded in concerns based on a rate of greater than three cases per million doses, and persistent high mortality in those developing VITT. The most recent information from the United Kingdom suggests an incidence for the AstraZeneca vaccine of 20.3 per million doses in those aged 18 to 49 years compared to 10.9 per million doses in those aged 50 years and older. Earlier clinical recognition and awareness of VITT has reduced mortality from as high as 50 percent in initial case series to 5 percent in a recent analysis from Australia. An updated CDC review in December 2021, based on better case ascertainment following description of the syndrome, has now estimated the incidence to be as high as 1 in 100,000. The risk appears far lower for the two mRNA vaccines.įollowing the initial April 2021 FDA/CDC review of all sources of event reporting in the United States following JJ vaccine administration, and a detailed risk/benefit analysis, the CDC Advisory Committee on Immunization Practices recommended that the JJ vaccine remain available in the United States for persons aged 18 years and older. This syndrome has been termed “vaccine-induced prothrombotic immune thrombocytopenia (VIPIT)” or “vaccine-induced immune thrombotic thrombocytopenia (VITT),” and “thrombosis with thrombocytopenia syndrome (TTS)” in communications from the CDC and FDA. Comprehensive clinical and laboratory characteristics of VITT have been reported in retrospective series and a large prospective cohort. This announcement came on the heels of the initial reports of similar events in individuals receiving the CHaDOx1 nCov-19 AstraZeneca (AZ) vaccine outside the United States. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) suggested pausing administration of the Johnson & Johnson (JJ) vaccine to allow investigation of several cases of severe thrombosis with thrombocytopenia occurring post-vaccination. Use of a non-heparin anticoagulant may be indicated if patient is 4 to 42 days post–vaccine with all other facets of the syndrome pending PF4 ELISA testing and additional CBCs. *A patient who presents with thrombosis and a normal platelet count post-vaccination might be in an early stage of VITT. Continued assessment for development of thrombocytopenia/VITT is required. #To date, VITT appears far more likely following AstraZeneca/Johnson and Johnson adenoviral vaccines than Moderna/Pfizer mRNA vaccines. Knowledge about VITT continues to evolve, and updates will be made as new data become available. Consider referral to tertiary care center if VITT is confirmed.Avoid platelet transfusions unless other treatments have been initiated AND life-threatening bleeding or imminent surgery.If thrombocytopenia but no thrombosis and negative PF4 ELISA: likely ITP (see Q4).If thrombocytopenia and very high D-Dimer in absence of known thrombosis, particularly in the presence of severe headache, check PF4 ELISA, and consider treatment (see Q2).If PF4 ELISA returns negative and there is no thrombocytopenia, VITTis ruled out treat as standard venous thromboembolism. Confirmed thrombosis AND at least one of the following.Initiate therapy with intravenous immunoglobin and nonheparin anticoagulation pending PF4 ELISA results if:.PF4-ELISA (HIT assay) draw blood prior to any therapies.Imaging for thrombosis based on signs/symptoms.CBC with platelet count and peripheral smear.Initial work-up (a normal platelet count is less concerning for VITT*):.Avoid use of heparin until VITT has been ruled out or until an alternative other plausible diagnosis has been made. If thrombocytopenia or thrombosis are present, recommend urgent consultation from hematologist with expertise in hemostasis.If VITT is suspected, perform immediate CBC with platelet count and imaging for thrombosis based on symptoms.Urgent medical evaluation for VITT is indicated if any of the following develop 4 to 42 days after vaccination:. ![]() Incidence is extremely low. Risk of death and serious outcomes of COVID-19, including thrombosis, far outweigh risk of VITT possibly associated with highly efficacious vaccines. ![]()
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