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Haemophagocytic lymphohistiocytosis after ChAdOx1 nCoV-19 vaccination
  1. Luke Attwell1,
  2. Than Zaw2,
  3. Jill McCormick1,
  4. Jonathan Marks3,
  5. Helen McCarthy2
  1. 1 Department of Haematology, Dorset County Hospital NHS Foundation Trust, Dorchester, UK
  2. 2 Department of Haematology, University Hospitals Dorset NHS Foundation Trust, Bournemouth, UK
  3. 3 Department of Rheumatology, University Hospitals Dorset NHS Foundation Trust, Bournemouth, UK
  1. Correspondence to Dr Luke Attwell, Haematology, Dorset County Hospital NHS Foundation Trust, Dorchester DT1 2JY, UK; lukeattwell{at}

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We report three cases of haemophagocytic lymphohistiocytosis (HLH) following the ChAdOx1 Astrazeneca vaccine. HLH is a rare but often fatal dysregulated hyperimmune response that clinically resembles sepsis.1 It is classified as either familial, with known genetic defects in lymphocyte cytotoxicity identified (such as PRF1 or UNC13D mutations) or acquired/secondary HLH (sHLH). sHLH in adults is usually secondary to infection, malignancy or autoimmune disease, although HLH triggered by conventional vaccination such as influenza has been reported.2

The pathogenesis of sHLH is poorly understood but results from disruption to immune homeostasis, with aberrant activation of T cells, natural killer cells and macrophages leading to overproduction of inflammatory cytokines such as tumour necrosis factor (TNF)-alpha,TNF-gamma, interleukin (IL)-1, IL-2, IL-6 and haemophagocytosis.

Patients present with recurrent fever, cytopaenia, liver dysfunction, organomegaly, elevated ferritin and inflammatory markers and can rapidly progress to multiorgan failure. Early symptoms are often non-specific including wasting, fatigue, purpura, dyspnoea, diarrhoea, bleeding, rash, arthralgia and lymphadenopathy.3 The Histiocyte Society diagnostic criteria (HLH-2004) that were developed for paediatric-HLH diagnosis are commonly used in adult sHLH.

Patient 1, a male in his 60s with tablet-controlled type 2 diabetes mellitus was admitted to hospital 10 days after receiving the first dose of the ChAdOx1 vaccine. He presented with breathlessness, fevers and myalgia with onset of symptoms 5 days postvaccination. He was commenced on broad spectrum antibiotics for presumed infection. CT pulmonary angiography excluded pulmonary emboli but highlighted bilateral pleural effusions. Echocardiogram showed normal biventricular systolic function. An elevated …

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  • Handling editor Mary Frances McMullin.

  • Contributors All authors have contributed to drafting, revision and approval of the manuscript. LA and HM are responsible for the final version.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.