We read with interest Hafeez et al. discussion regarding concern about haemostatic
adverse effects post vaccination.[1] Many haemostatic complications
post COVID-19 vaccination have been reported including the syndrome of
thrombocytopenia and thrombosis, as discussed by Hafeez et al.[1]In 2019, a new pandemic of coronavirus arose from China and quickly spread across the
world.[2] It became a public health emergency.[2] Covid-19 infection usually
begin with flu like symptoms however, about 10% of the symptomatic subjects may
experience more severe course of the disease.[2] Vaccination became the
cornerstone strategy in disease control and prevention of new and more severe cases
of COVID-19 infection.[2]Here we would like to add to the haemostatic adverse events post vaccination reported
by Hafeez et al. and report a case of Acquired Haemophilia A (AHA) one week
following a Pfizer-BioNTech SARS-CoV-2 vaccine. AHA is a rare bleeding disorder
(reported incidence; 1 per million/year) which results in spontaneous bleeding in
people with no history of a bleeding disorder.[3] It is believed to be caused by
autoantibodies directed against factor VIII (FVIII).[3] It most often seen in elderly
patients and is often associated with autoimmune conditions or malignancies but many
cases are idiopathic.[3] Here we discuss the rare occurrence of AHA post
vaccination.A 72-year-old gentleman developed forearm, arm and thigh bruising approximately one
week after receiving the first dose of the Pfizer-BioNTech COVID-19 vaccine in April
2021. He attended his family doctor when the bruising extended, who referred him
urgently to hospital. He had a history of successfully treated prostate carcinoma
[prostate-specific antigen was 0.07 ng/ml (normal range = 0-4 ng/ml)], non-insulin
dependent diabetes and hypertension. His physical examination was unremarkable other
than tongue swelling and extensive bruising. Bloods showed anaemia (haemoglobin:
79 g/L), a normal platelet count (288 × 109/L, a prolonged activated
partial thromboplastin time [APTT] of 71 s [normal range = 25.1-36.5 s] and a normal
prothrombin time and fibrinogen. His lupus anticoagulant screen was negative. The
Factor VIII level was reduced [0.01IU/ml [normal range = 0.50 to 1.49 IU/ml]] and
Factor VIII inhibitor quantification demonstrated an inhibitor of 70 B.U/ml,
consistent with a diagnosis of acquired Haemophilia A. He was treated with one dose
[4500 units] of FVIII inhibitor bypassing activity [FEIBA] to control the bleeding
and prednisolone 60 mg once daily [reduced dose due to age and history of diabetes].
He experienced no further bleeding episodes. CT imaging showed no evidence of
malignancy. He completed four weekly doses of rituximab 375 mg/m2 and
underwent a slow steroid taper. His FVIII level was normal and his inhibitor screen
negative 6 weeks after diagnosis. Remission has persisted despite stopping all
immunosuppression.According to the European Centre for Disease Prevention and Control, 82.2% of adults
have had at least one dose of a covid-19 vaccine and this rises to >94% in
Ireland.[4] Pharmacovigilance is key when new medications or vaccines are
introduced, especially to such a large proportion of the worlds’ population as rare
complications are likely to be seen.[5] Adverse Events Following
Immunisation (AEFI) are reported in 53.7 per 100,000 COVID-19 vaccine doses
administered.[6] The most common adverse events associated with the COVID-19
vaccine to date are allergic skin reactions and pain/redness/swelling at the
injection site. Serious AEFI was reported in 2.8 per 100,000 doses of COVID-19
vaccine administered.[6] Four other cases of AHA following SARS-CoV-2 vaccination
have been reported to date.[7-10] Education about pharmacovigilance and trust in the system is
key to limit vaccine scepticism.[5]The potential correlation between vaccinations and autoimmune disease has been
postulated for a long time.[4] The pathogenetic mechanism and aetiology of this is still
unclear.[5] It has been suggested that the mechanism of autoimmune disease
development post vaccination is by molecular mimicry, by which viral or bacterial
agents trigger an immune response against autoantigens.[5] Another hypothesis is;
bystander activation, which involves the activation of quiescent auto-reactive T and
B cells.[5]
However, it is suggested that some people are more susceptible to developing these
reactions due to a genetic predisposition to autoimmune diseases.[5] This hypothesis
may explain the pathogenesis of AHA post SARS-CoV-2 vaccine.COVID-19 infection rates are rising worldwide.[4] Booster doses are being
administered and the vaccination programme is being expanded to children.[4] More
haemostatic adverse events post vaccination are likely to be seen. Therefore,
ongoing pharmacovigilance is required.