Background rate estimations for thrombosis with thrombocytopaenia: challenges in evaluating rare safety signals following vaccination in real time during a pandemic

Article Immunology

Expected Rates of Select Adverse Events After Immunization for Coronavirus Disease 2019 Vaccine Safety Monitoring

Winston E. Abara et al.

Summary: Using meta-analytic methods, researchers calculated the expected rates of potential adverse events after COVID-19 vaccination. The results provide critical information for vaccine safety monitoring and benefit-risk assessment.

JOURNAL OF INFECTIOUS DISEASES (2022)

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Article Public, Environmental & Occupational Health

Background rates of five thrombosis with thrombocytopenia syndromes of special interest for COVID-19 vaccine safety surveillance: Incidence between 2017 and 2019 and patient profiles from 38.6 million people in six European countries

Edward Burn et al.

Summary: The study found that non-vaccine induced TTS is a very rare event among the general population, with higher rates typically seen in older individuals, males, as well as those with more comorbidities and greater medication use.

PHARMACOEPIDEMIOLOGY AND DRUG SAFETY (2022)

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Article Immunology

Thrombosis with thrombocytopenia after AZD1222 (ChAdOx1 nCov-19) vaccination: Case characteristics and associations

Michael A. Laffan et al.

Summary: This study analyzed 573 cases of thrombosis with thrombocytopenia syndrome (TTS) reported post-AZD1222 vaccination, indicating potential unidentified risk factors in some cases. The decreasing fatality rate correlated with increasing awareness and publication of diagnostic/treatment guidelines. The study highlights the importance of comprehensive reporting to further improve the definition and management of this extremely rare syndrome.

VACCINE (2022)

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Article Immunology

The critical role of background rates of possible adverse events in the assessment of COVID-19 vaccine safety

Steven B. Black et al.

Summary: Post-introduction safety evaluation of COVID-19 vaccines is crucial for monitoring potential risks, involving the dynamic list of Adverse Events of Special Interest (AESI) and establishing background rates to identify safety concerns in a timely manner.

VACCINE (2021)

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Article Medicine, General & Internal

Thrombosis and Thrombocytopenia after ChAdOx1 nCoV-19 Vaccination

Nina H. Schultz et al.

Summary: This study reports five cases of venous thrombosis and thrombocytopenia occurring 7 to 10 days after receiving the ChAdOx1 nCoV-19 vaccine, suggesting a rare vaccine-induced immune thrombotic thrombocytopenia. The condition, which can lead to catastrophic outcomes such as cerebral venous sinus thrombosis, may be treated with intravenous immune globulin.

NEW ENGLAND JOURNAL OF MEDICINE (2021)

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Article Medicine, General & Internal

Thrombotic Thrombocytopenia after ChAdOx1 nCov-19 Vaccination

Andreas Greinacher et al.

Summary: After vaccination with ChAdOx1 nCov-19, rare immune thrombotic thrombocytopenia can occur due to platelet-activating antibodies against PF4, resulting in various thrombotic events. Most patients in this case series were women, with fatal outcomes such as cerebral venous thrombosis and intracranial hemorrhage. Additional studies are needed to further investigate and understand this phenomenon.

NEW ENGLAND JOURNAL OF MEDICINE (2021)

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Article Public, Environmental & Occupational Health

Methodological frontiers in vaccine safety: qualifying available evidence for rare events, use of distributed data networks to monitor vaccine safety issues, and monitoring the safety of pregnancy interventions

Caitlin Dodd et al.

Summary: Vaccines undergo rigorous testing in clinical trials, but may not detect rare adverse events or include certain populations like pregnant women. Postmarketing safety assessments are needed using observational data sources, large databases, and distributed networks. Developing common protocols, definitions, and tools for assessing real-world vaccine safety evidence is necessary for future surveillance.

BMJ GLOBAL HEALTH (2021)

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Letter Medicine, General & Internal

Very rare thrombosis with thrombocytopenia after second AZD1222 dose: a global safety database analysis

Prakash Bhuyan et al.

LANCET (2021)

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Article Medicine, General & Internal

Cerebral venous thrombosis after vaccination against COVID-19 in the UK: a multicentre cohort study

Richard J. Perry et al.

Summary: The study documented cases of cerebral venous thrombosis after COVID-19 vaccination, finding that patients with VITT were younger, had more intracranial and extracranial thrombosis, and experienced worse outcomes compared to non-VITT patients. Treatments with non-heparin anticoagulants and intravenous immunoglobulin may improve outcomes in VITT-associated cerebral venous thrombosis.

LANCET (2021)

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Article Medicine, General & Internal

Clinical Features of Vaccine-Induced Immune Thrombocytopenia and Thrombosis

Sue Pavord et al.

Summary: Phenotypes of VITT were defined in 220 patients in the United Kingdom who presented a median of 14 days after the first ChAdOx1 nCoV-19 vaccination. Half had cerebral venous sinus thrombosis, a third of whom also had intracranial hemorrhage. Mortality was 22%. Intravenous immune globulin may reverse VITT.

NEW ENGLAND JOURNAL OF MEDICINE (2021)

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Article Medicine, General & Internal

Risk of thrombocytopenia and thromboembolism after covid-19 vaccination and SARS-CoV-2 positive testing: self-controlled case series study

Julia Hippisley-Cox et al.

Summary: The study found increased risks of haematological and vascular events leading to hospital admission or death within short time intervals after first doses of the ChAdOx1 nCoV-19 and BNT162b2 mRNA vaccines. The risks of these events were higher and more prolonged after SARS-CoV-2 infection compared to vaccination in the same population.

BMJ-BRITISH MEDICAL JOURNAL (2021)

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Editorial Material Public, Environmental & Occupational Health