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Histological and serological features of acute liver injury after SARS-CoV-2 vaccination

Open AccessPublished:October 12, 2022DOI:https://doi.org/10.1016/j.jhepr.2022.100605

      Highlights

      • 59 patients with acute liver injury after SARS-CoV-2 vaccine
      • Histology shows mostly lobular hepatitis without relevant fibrosis
      • 65% ANA positive, 54% SMA positive,35% elevated IgG
      • Normal transaminases in 65% of the cases at 6 months, one liver transplantation

      Abstract

      Background & Aims

      Liver injury with autoimmune features after vaccination against Severe Acute Respiratory Syndrome Coronavirus type 2 (SARS-CoV-2) is increasingly reported. We investigated a large international cohort of patients with acute hepatitis arising after SARS-CoV-2 vaccination, focusing on histological and serological features.

      Approach & Results

      Patients without known pre-existing liver diseases and transaminase levels ≥5x the upper limit of normal within 3 months after any anti-SARS-CoV-2 vaccine and available liver biopsy are included. Fifty-nine patients were recruited; 35 females; median age 54 years; they were exposed to various combinations of mRNA, vectorial, inactivated and protein-based vaccines. Liver histology showed predominantly lobular hepatitis in 45 (76%) cases, predominantly portal hepatitis in 10 (17%), and other patterns in four (7%); seven had fibrosis Ishak stage ≥3, associated with more severe interface hepatitis. Autoimmune serology, centrally tested in 31 cases, showed anti-antinuclear antibody in 23 (74%), anti-smooth muscle antibody in 19 (61%), anti-gastric parietal cells in 8 (26%), anti-liver kidney microsomal in 4 (13%), anti-mitochondrial antibody in 4 (13%). Ninety-one percent were treated with steroids, ± azathioprine. Serum transaminase levels improved in all cases, and were normal in 24/58 (41%) after three months, and in 30/46 (65%) after six months. One patient required liver transplantation. Re-exposure to SARS-CoV-2 vaccines of 15 patients resulted in three relapses.

      Conclusion

      Acute liver injury arising after SARS-CoV-2 vaccination is frequently associated with lobular hepatitis and positive autoantibodies. Whether there is a causal relationship between liver damage and SARS-CoV-2 vaccines remains to be established. A close follow-up is warranted to assess the long-term outcome of this condition.

      Lay summary

      Cases of liver injury after vaccination against Severe Acute Respiratory Syndrome Coronavirus type 2 (SARS-CoV-2) have been published. We investigated a large international cohort of patients with acute hepatitis after SARS-CoV-2 vaccination, focusing on liver biopsy findings and autoantibodies: liver biopsy frequently shows inflammation of the lobule, which is typical of recent injury, and autoantibodies are frequently positive. Whether there is a causal relationship between liver damage and SARS-CoV-2 vaccines remains to be established. Close follow-up is warranted to assess the long-term outcome of this condition.

      Graphical abstract

      Keywords

      List of abbreviations:

      SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus type 2), COVID-19 (Coronavirus disease 2019), AIH (Autoimmune Hepatitis), IgG (Immunoglobulin G), IAIHG (International Autoimmune Hepatitis Group), ULN (Upper limit of normal), ALT (Alanine aminotransferase), AST (Aspartate aminotransferase), ALP (Alkaline phosphatase), IFT (Indirect immunofluorescence), ANA (Anti-nuclear antibody), LKM (Liver kidney microsomal), AMA (Anti-mitochondrial antibody), SLA (Soluble liver antigen), pIgG (Polyreactive immunoglobulin G), PCA (Parietal cell antigen), SMA (Anti-smooth muscle antibody), DILI (Drug-induced liver injury), LT (Liver transplantation)

      1. Introduction

      The ongoing pandemic caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), a highly transmissible and pathogenic virus leading to coronavirus disease 2019 (COVID-19), is having a devastating global impact, leading to an unprecedented fast development of anti-COVID-19 vaccines. The vaccines are highly effective in preventing COVID-19, particularly in reducing the incidence of severe and fatal outcomes
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      While registration trials did not detect liver injury as a side effect of SARS-CoV-2 vaccines, immunization of billions of people has led to the report of an increasing number of cases of acute hepatitis following vaccination
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      The mRNA COVID-19 vaccine - a rare trigger of Autoimmune Hepatitis?.
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      Autoimmune hepatitis triggered by SARS-CoV-2 vaccination.
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      COVID-19 vaccine and autoimmunity. A new case of autoimmune hepatitis and review of the literature.
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      • Carneiro F.
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      Autoimmune hepatitis after COVID-19 vaccine - more than a coincidence.
      • Avci E.
      • Abasiyanik F.
      Autoimmune hepatitis after SARS-CoV-2 vaccine: New-onset or flare-up?.
      • Guardiola J.
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      • Chalasani N.
      Unexplained liver test elevations after SARS-CoV-2 vaccination.
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      • Todd N.J.
      • VanWagner L.B.
      Liver injury following SARS-CoV-2 vaccination: A multicenter case series.
      • Chow K.W.
      • Pham N.V.
      • Ibrahim B.M.
      • Hong K.
      • Saab S.
      Autoimmune Hepatitis-Like Syndrome Following COVID-19 Vaccination: A Systematic Review of the Literature.
      . According to a retrospective study carried out in the USA, the frequency of unexplained elevation of liver tests after SARS-CoV-2 vaccines is 0.038%, being lower than the frequency after influenza vaccination
      • Guardiola J.
      • Lammert C.
      • Teal E.
      • Chalasani N.
      Unexplained liver test elevations after SARS-CoV-2 vaccination.
      .
      Case reports of acute hepatitis arising after SARS-CoV-2 vaccines often show positive autoantibodies, elevated immunoglobulin G (IgG) levels, interface hepatitis at liver histology and response to immunosuppressive treatment, raising the question as to whether this condition may be autoimmune hepatitis (AIH) triggered by the vaccination
      • Bril F.
      • Al Diffalha S.
      • Dean M.
      • Fettig D.M.
      Autoimmune hepatitis developing after coronavirus disease 2019 (COVID-19) Vaccine: Causality or casualty?.
      ,
      • McShane C.
      • Kiat C.
      • Rigby J.
      • Crosbie Ó.
      The mRNA COVID-19 vaccine - a rare trigger of Autoimmune Hepatitis?.
      • Londoño M.-C.
      • Gratacós-Ginès J.
      • Sáez-Peñataro J.
      Another case of autoimmune hepatitis after SARS-CoV-2 vaccination.
      • Rela M.
      • Jothimani D.
      • Vij M.
      • Rajakumar A.
      • Rammohan A.
      Auto-immune hepatitis following COVID vaccination.
      • Vuille-Lessard É
      • Montani M.
      • Bosch J.
      • Semmo N.
      Autoimmune hepatitis triggered by SARS-CoV-2 vaccination.
      • Camacho-Domínguez L.
      • Rodríguez Y.
      • Polo F.
      • Restrepo Gutierrez J.C.
      • Zapata E.
      • Rojas M.
      • et al.
      COVID-19 vaccine and autoimmunity. A new case of autoimmune hepatitis and review of the literature.
      • Garrido I.
      • Lopes S.
      • Simões M.S.
      • Liberal R.
      • Lopes J.
      • Carneiro F.
      • et al.
      Autoimmune hepatitis after COVID-19 vaccine - more than a coincidence.
      ,
      • Chow K.W.
      • Pham N.V.
      • Ibrahim B.M.
      • Hong K.
      • Saab S.
      Autoimmune Hepatitis-Like Syndrome Following COVID-19 Vaccination: A Systematic Review of the Literature.
      . A tertiary center in Germany, however, has not observed an increased incidence of AIH cases in 2021, after the introduction of the SARS-CoV-2 vaccines
      • Rüther D.F.
      • Weltzsch J.P.
      • Schramm C.
      • Sebode M.
      • Lohse A.W.
      Autoimmune hepatitis and COVID-19: No increased risk for AIH after vaccination but reduced care.
      . Classical AIH is a rare chronic inflammatory liver condition characterized by female preponderance, high transaminase and serum IgG levels, positive autoantibodies, interface hepatitis at liver histology and a swift response to steroid treatment
      • Mieli-Vergani G.
      • Vergani D.
      • Czaja A.J.
      • Manns M.P.
      • Krawitt E.L.
      • Vierling J.M.
      • et al.
      . As current knowledge mostly stems from case reports, little is known on key clinical, histological and immunological features of SARS-CoV-2 vaccine-associated liver injury. The aim of this international study was to collect clinical, pathological and serological data of a large number of patients with acute liver injury diagnosed after a SARS-CoV-2 vaccination and review them centrally in order to define the key characteristics of this novel condition.

      2. Methods

      2.1 Study population

      Cases were collected from members of the International AIH Group (IAIHG) and the European Reference Network on Hepatological Diseases (ERN RARE-LIVER). Inclusion criteria were: elevation of transaminase levels ≥5x the upper limit of normal (ULN) occurring within 3 months from any vaccination against SARS-CoV-2 with available liver biopsy for central review and a clinical follow-up of at least 3 months or until liver transplantation (LT)/death, whichever came first, from diagnosis of acute liver injury. Exclusion criteria were: a known history of autoimmune liver disease (AIH; primary biliary cholangitis; primary sclerosing cholangitis); acute or chronic viral hepatitis including hepatitis A, B, C, D or E; history of LT.
      All patients gave written informed consent. All procedures were conducted in accordance with the appropriate ethics committee.

      Definitions:

      Heterologous vaccination = exposure to a combination of vaccines (mRNA, vectorial, inactivated or protein-based).
      Remission = alanine aminotransferase (ALT) normalization at three months after diagnosis
      • Andrade R.J.
      • Lucena M.I.
      • Kaplowitz N.
      • García-Muņoz B.
      • Borraz Y.
      • Pachkoria K.
      • et al.
      Outcome of acute idiosyncratic drug-induced liver injury: Long-term follow-up in a hepatotoxicity registry.
      .
      Relapse = any increase of transaminase levels after initial improvement.
      The following variables were collected at diagnosis: sex; age at liver injury; date and name of each vaccine dose against SARS-CoV-2; date of hepatitis diagnosis; date of liver biopsy; re-exposure to a SARS-CoV-2 vaccine after the diagnosis of hepatitis; liver biochemistry and INR at diagnosis, and three and six months after the diagnosis of hepatitis; concomitant autoimmune diseases; concomitant medications; medications for vaccine side effects; local autoantibody testing; treatment for hepatitis including name and dose of drug, date of treatment start and cessation. The liver injury pattern was categorized according to the R ratio value, defined as serum ALT / ULN divided by serum alkaline phosphatase (ALP) / ULN: R >5 defines a hepatocellular pattern of injury, R between 2 and 5 defines a mixed pattern, and R < 2 defines a cholestatic pattern
      • Fontana R.J.
      • Seeff L.B.
      • Andrade R.J.
      • Björnsson E.
      • Day C.P.
      • Serrano J.
      • et al.
      Standardization of nomenclature and causality assessment in drug-induced liver injury: summary of a clinical research workshop.
      . Clinical severity of the liver injury was assessed according to the original and revised Hy’s laws
      • Robles-Diaz M.
      • Lucena M.I.
      • Kaplowitz N.
      • Stephens C.
      • Medina-Cáliz I.
      • González-Jimenez A.
      • et al.
      Use of Hy’s law and a new composite algorithm to predict acute liver failure in patients with drug-induced liver injury.
      ,
      European Association for the Study of the Liver
      Electronic address: [email protected], Clinical Practice Guideline Panel: Chair:, Panel members, EASL Governing Board representative: EASL Clinical Practice Guidelines: Drug-induced liver injury.
      .

      2.2 Histology

      Liver biopsies were reviewed by an experienced histopathologist (YZ). Glass or digital slides were sent to the central reviewer, and inflammatory activity and fibrosis stages were assessed according to the modified Ishak’s scoring system
      • Ishak K.
      • Baptista A.
      • Bianchi L.
      • Callea F.
      • De Groote J.
      • Gudat F.
      • et al.
      Histological grading and staging of chronic hepatitis.
      . Only scarring fibrosis, but not collapsed stroma, was counted for fibrosis staging. Plasma cell or eosinophilic aggregates defined as the presence of ≥5 cells in a circular spot with a diameter of 150 μm were assessed. Finally, the recently proposed AIH pathological criteria were also applied, in addition to the simplified IAIHG criteria
      • Lohse A.W.
      • Sebode M.
      • Bhathal P.S.
      • Clouston A.D.
      • Dienes H.P.
      • Jain D.
      • et al.
      Consensus Recommendations for Histological Criteria of Autoimmune Hepatitis from the International AIH Pathology Group.
      ,
      • Hennes E.M.
      • Zeniya M.
      • Czaja A.J.
      • Parés A.
      • Dalekos G.N.
      • Krawitt E.L.
      • et al.
      Simplified criteria for the diagnosis of autoimmune hepatitis.
      .

      2.3 Autoantibodies

      Serum was available for central testing for 31 patients. Autoantibody diagnostic was performed after shipment of frozen serum samples at Hannover Medical School, Hannover/Germany. The presence of autoantibodies was tested in all serum samples via indirect immunofluorescence (IFT) on sections of frozen rodent liver, stomach and kidney (AESKUSLIDES, AESKU-Diagnostics) and on HEp2 cells (ZENIT-Autoimmunity Reagents, Menarini Diagnostics) as recommended by current guidelines
      • Vergani D.
      • Alvarez F.
      • Bianchi F.B.
      • Cançado E.L.R.
      • Mackay I.R.
      • Manns M.P.
      • et al.
      Liver autoimmune serology: a consensus statement from the committee for autoimmune serology of the International Autoimmune Hepatitis Group.
      , and via a liver line immunoassay (IMTEC-Leber-LIA, Human Gesellschaft für Biochemie und Diagnostika) including target antigens for anti-liver kidney microsomal (LKM) type 1 (CYP2D6), anti-mitochondrial (AMA) (pyruvate dehydrogenase-E2), anti-soluble liver antigen (SLA) (O-Phosphoseryl-TRNA(Sec) Selenium Transferase), anti-gp210 and anti-sp100 antibodies. Sera giving a LKM pattern were further investigated by western blots against CYP2D6, CYP2C9 and family 1 uridine 5’-diphosphate glucuronosyltransferase (LKM-1, 2 and 3, respectively). In case of positive staining of parietal cells on frozen stomach sections, samples were subsequently tested for presence of IgG antibodies against parietal cell (PCA) via a line immunoassay (Gastro-5-Line, Orgentec Diagnostika). The presence of polyreactive immunoglobulin G (pIgG), reported to be elevated in untreated AIH and more specific and accurate to distinguish AIH from non-AIH liver diseases, was tested via a custom-made ELISA containing bovine serum albumin (BSA) as blocking reagent and huntingtin-interacting protein 1-related protein (HIP1R) as autoantigen in a single 1:100 dilution as published recently
      • Taubert R.
      • Engel B.
      • Diestelhorst J.
      • Hupa-Breier K.L.
      • Behrendt P.
      • Baerlecken N.T.
      • et al.
      Quantification of polyreactive immunoglobulin G facilitates the diagnosis of autoimmune hepatitis.
      .

      2.4 Statistical analysis

      Categorical variables are expressed as numbers and percentages; continuous variables are expressed as median and range. Statistical analysis was performed using SPSS Version 22.0. The Fisher’s exact test was used to compare categorical data between two groups. The Mann-Whitney U test was used to compare quantitative data between two groups. P-values below 0.05 (two-tailed) were considered significant in all analyses.

      3. Results

      3.1 Clinical features

      The patient characteristics at the time of the hepatitis diagnosis, treatment and outcomes are summarized in Table 1. Data of eleven patients have been previously published, before the centralized histological and serological evaluation presented here; their follow up has been updated
      • Ghielmetti M.
      • Schaufelberger H.D.
      • Mieli-Vergani G.
      • Cerny A.
      • Dayer E.
      • Vergani D.
      • et al.
      Acute autoimmune-like hepatitis with atypical anti-mitochondrial antibody after mRNA COVID-19 vaccination: A novel clinical entity?.
      ,
      • Vuille-Lessard É
      • Montani M.
      • Bosch J.
      • Semmo N.
      Autoimmune hepatitis triggered by SARS-CoV-2 vaccination.
      ,

      Efe C, Kulkarni AV, Beretta-Piccoli BT, Magro B, Stättermayer AF, Cengiz M, et al. Liver injury after SARS-CoV-2 vaccination: Features of immune-mediated hepatitis, role of corticosteroid therapy and outcome. Hepatology [Internet]. [cited 2022 May 14];n/a. Available from: https://onlinelibrary.wiley.com/doi/abs/10.1002/hep.32572.

      • Pinazo-Bandera J.M.
      • Hernández-Albújar A.
      • García-Salguero A.I.
      • Arranz-Salas I.
      • Andrade R.J.
      • Robles-Díaz M.
      Acute hepatitis with autoimmune features after COVID-19 vaccine: coincidence or vaccine-induced phenomenon?.
      • Torrente S.
      • Castiella A.
      • Garmendia M.
      • Zapata E.
      Probable autoimmune hepatitis reactivated after COVID-19 vaccination.
      .
      Table 1Demographic and clinical data of patients with liver injury after vaccination against SARS-CoV-2.
      n=59n%median (range)
      Sexfemale/male35/2459/41
      Age54 (19 - 92)
      SARS-CoV-2 infection before liver injury59
      Vaccination
      Heterologous vaccination814
      Last vaccine before liver injurymRNA-1273 (Moderna)1220
      BNT162b2 (Pfizer)3051
      AZD1222 (AstraZeneca)1119
      Gam-COVID-Vac (Sputnik V)59
      BBIBP-CorV (Sinopharm)12
      Number of vaccinations before liver injury12034
      23763
      323
      Vaccine to hepatitis (days)24 (1 - 74)
      Medication for vaccine side effectsno3356
      yes58
      unknown2136
      Laboratory values at diagnosis
      ALT/ULN24.0 (5.0- 111.3)
      AST/ULN22.1 (3.0-169.1)
      ALP/ULN1.4 (0.5- 8.2)
      GGT/ULN4.3 (0.4-39.0)
      Total bilirubin/ULN (n=56)4.7 (0.4-34.4)
      INR (n=57)1.2 (0.7- 3.2)
      IgG (g/l) (n=58)

      IgG >16g/l
      17.3 (6.6-39.9)
      4068
      IgM (g/l) (n=48)1.2 (0.2- 9.8)
      Original Hy's law satisfied (n=56)3257
      New Hy's law satisfied (n=56)3054
      Liver injury pattern R ratio (n=58)hepatocellular (R≥5)5595
      mixed (R 2-5)35
      Centralized liver biopsy Ishak score (n=59)
      Interface hepatitis2 (0-4)
      Confluent necrosis2 (0-6)
      Lobular hepatitis3 (0-4)
      Portal inflammation2 (0-3)
      Total necro-inflammatory activity9 (0-14)
      Fibrosis1 (0-6)
      Simplified IAIHG criteriatypical1424
      compatible3458
      atypical1119
      New histological criteria
      • Lohse A.W.
      • Sebode M.
      • Bhathal P.S.
      • Clouston A.D.
      • Dienes H.P.
      • Jain D.
      • et al.
      Consensus Recommendations for Histological Criteria of Autoimmune Hepatitis from the International AIH Pathology Group.
      likely4170
      possible1322
      unlikely58
      Local autoantibody testing
      ANA HEp2 cells (n=58)positive4374
      ANA titers HEp2 cells≥1: 16028/4365
      ANA pattern HEp2 cells (n=34)homogeneous16
      fine speckled/speckled13
      nucleolar4
      mixed (homogeneous+speckled)2
      Cytoplasmatic pattern HEp2 cells35
      reticular2
      granular1
      SMA (n=59)positive2237
      SMA titer≥1: 1601255
      Anti-LKM (n=52)positive48
      anti LKM titer1:1604
      anti LC1 (n=32)positive0
      anti SLA (n=45)positive0
      AMA (n=55)positive59
      AMA titer1:≥ 1604
      ANCA (n=35)positive (1:1280)13
      Treatment of post-vaccine hepatitis
      Immunosuppression (steroids ± azathioprine)5288
      Days from liver biopsy to treatment start2 (-107 - 254)
      Steroids therapy (Prednisolone equivalent)50 mg/day (10-625)
      Azathioprine addition to steroids71250 mg/day (25-150)
      Outcome
      Outcome (n=59)spontaneous remission59
      relapse treated with steroids after spontaneous remission23
      remission with IS & successful IS withdrawal1017
      remission with IS & IS withdrawal still ongoing2339
      remission with IS & IS withdrawal failure47
      improvement but no remission despite IS treatment1220
      liver transplantation12
      death, non liver-related*35
      SARS-CoV-2, Severe Acute Respiratory Coronavirus 2; IgG Immunoglobulin, G; ULN, upper limit of normal; ALT, alanine aminotransferase; INR, international normalized ratio; AST, aspartate aminotransferase; GGT, gamma-glutamyl-transferase; IAIHG, international autoimmune hepatitis group; SMA, anti-smooth muscle antibody; ALP, alkaline phosphatase; ANA, anti-nuclear antibody; LKM, liver kidney microsomal; AMA, anti-mitochondrial antibody; SLA, soluble liver antigen; ANCA, anti-neutrophil cytoplasmic antibody; IS, immunosuppression; R ratio: ALT/ULN divided by ALP/ULN.
      Fifty-nine patients, from 26 centers in 11 Countries were recruited according to the inclusion and exclusion criteria. The majority were female, median age at diagnosis of hepatitis was 54 years. Five had a history of COVID-19 before hepatitis (Figure 1). Patients were exposed to seven different SARS-CoV-2 vaccines [mRNA based vaccines: mRNA-1273 (Moderna) and BNT162b2 (Biontech/Pfizer); non-replicative virus vector vaccines: AZD1222 (AstraZeneca), Ad26.COV2.S (Johnson & Johnson) and Gam-COVID-Vac (Sputnik V); vaccine with inactivated SARS-CoV-2: BBIBP-CorV (Sinopharm); and protein based vaccines: NVX-CoV2373 (Novavax)] in various combinations before the diagnosis of liver injury (Figure 1). The hepatitis was diagnosed after the second vaccine dose in the majority of patients (Table 1). The median time from last vaccine dose to diagnosis of hepatitis was 24 days. Thirty-six patients (61%) were on other medications and/or had a history of other medications in the 12 weeks preceding the liver injury (Supplementary Table 1); none was on steroids, while three were on immunosuppressants (azathioprine, anti-CD20, anti-IL23). Eighteen (31%) had an extrahepatic autoimmune comorbidity (Supplementary Table 2). Five took medications to treat vaccine side effects, including acetaminophen at a dose of 1-1.5 g/day in all cases, and diclofenac in one case.
      Figure thumbnail gr1
      Figure 1Sequence of SARS-CoV-2 vaccinations and COVID-19 infections before the onset of liver injury.
      Laboratory test values obtained at presentation in the participating centers were normalized to the local ULN (Table 1 and Figure 2). The liver enzyme pattern was hepatocellular in the vast majority of the cases and mixed in a small minority; none had a cholestatic pattern
      • Fontana R.J.
      • Seeff L.B.
      • Andrade R.J.
      • Björnsson E.
      • Day C.P.
      • Serrano J.
      • et al.
      Standardization of nomenclature and causality assessment in drug-induced liver injury: summary of a clinical research workshop.
      . Total IgG were elevated (> 16g/l) in two thirds of the cases (Table 1). Acute liver failure including hepatic encephalopathy manifested in a single patient, the only to require LT (113 days after re-exposure to BNT162b2 vaccine).
      Figure thumbnail gr2
      Figure 2Longitudinal development of biochemistry tests in liver injuries associated with SARS-CoV-2 vaccines.

      3.2 Histology

      Centralized liver biopsy Ishak’s score is summarized in Table 1.
      According to the predominant pattern of injury, the cases were classified into the following categories (Figures 3 and 4):
      Figure thumbnail gr3
      Figure 3Histology of liver injury associated with SARS-CoV-2. The histological injury pattern can be categorized into predominant lobular (left column) as well as predominant portal (mid column) injury pattern, each with subclassifications (lower panels), and a small group of different manifestations (right column).
      Figure thumbnail gr4
      Figure 4Representative histological pattern of liver injury associated with SARS-CoV-2. Outlined are representative examples for the histological types from : A) Lobular hepatitis with confluent necrosis (x100); B) Panlobular hepatitis (x200); C) Isolated central perivenulitis; D) Portal hepatitis with interface injury (x100); E) Eosinophilic aggregates (x400) and F) Plasma cell aggregates (x400).

      Predominantly lobular injury (n=45, 76%)

      lymphocytic infiltration, focal necrosis and acidophilic bodies were observed in the parenchyma. Although most cases had portal inflammation, the necro-inflammatory changes were more conspicuous within the parenchyma than in the portal tracts. Variable degrees of confluent necrosis ranging from perivenular zonal necrosis to multiacinar parenchymal loss were identified in 33 cases, while seven cases showed features of panlobular hepatitis without confluent cell loss. The remaining five cases had a selective perivenular injury with confluent cell loss, in keeping with isolated central perivenulitis. Five cases among this group had conspicuous lobular cholestasis (cholestatic hepatitis). Another case also demonstrated multiple, small epithelioid granulomas in the parenchyma. None had cholangiopathic changes.

      Predominantly portal injury (n=10, 17%)

      portal-based lymphocytic infiltration was observed. Most cases had lobular inflammation and/or confluent necrosis, but the degree of inflammation was higher in portal tracts than in the parenchyma. Two cases had mild interface hepatitis, while eight cases showed more than mild interface injuries. None had cholangiopathic changes. Fibrosis stage was periportal fibrosis in six cases (Ishak’s stage 1-2), early bridging fibrosis in three cases (stage 3) and cirrhosis in one case (stage 6).
      Table 2 compares microscopic features between the two groups. As expected, the degrees of interface hepatitis and portal inflammation were higher in cases of predominantly portal injury, while the degrees of lobular inflammation and confluent necrosis were higher in cases of predominantly lobular injury. Fibrosis was more advanced in cases of portal injury than in those of lobular injury. Plasma cell aggregates were common in both groups (62-80%), and eosinophil aggregates were also seen in 40-50% of cases. According to the newly proposed AIH histopathology criteria, 70-80% of cases were classified as likely AIH
      • Lohse A.W.
      • Sebode M.
      • Bhathal P.S.
      • Clouston A.D.
      • Dienes H.P.
      • Jain D.
      • et al.
      Consensus Recommendations for Histological Criteria of Autoimmune Hepatitis from the International AIH Pathology Group.
      (Table 1).
      Table 2Histological comparison between cases of predominantly lobular or portal hepatitis.
      Lobular hepatitisPortal hepatitisp value
      (n=45)(n=10)
      Interface hepatitis
       0-123 (51%)2 (20%)0.041
       213 (29%)4 (40%)
       39 (20%)2 (20%)
       402 (20%)
      Confluent necrosis
       07 (16%)7 (70%)0.009
       1-212 (26%)2 (20%)
       3-417 (38%)1 (10%)
       5-69 (20%)0
      Lobular necroinflammation
       0-12 (4%)2 (20%)0.004
       213 (29%)6 (60%)
       316 (36%)2 (20%)
       414 (31%)0
      Portal inflammation
       0-113 (29%)00.005
       226 (58%)5 (50%)
       36 (13%)5 (50%)
       400
      Fibrosis
       06 (13%)00.006
       1-236 (80%)6 (60%)
       3-43 (7%)3 (30%)
       5-601 (10%)
      Inflammatory cells
       Plasma cell aggregate28 (62%)8 (80%)0.285
       Eosinophil aggregate18 (40%)5 (50%)0.562
      Histological criteria
       Likely32 (71%)8 (80%)0.572
       Possible13 (29%)2 (20%)
       Unlikely00
      Histological parameters were compared between cases of lobular and portal hepatitis using the Mann-Whitney U test. A probability of p<0.05 was considered to be significant.

      Other patterns of injury (n=4, 7%)

      Two cases showed bland cholestasis with bile casts in the canaliculi or the cytoplasm of hepatocytes, not associated with significant necro-inflammatory changes. One case showed features of active steatohepatitis. The last case had only minor microscopic changes.
      Clinical features of cases with predominantly lobular or predominantly portal hepatitis were similar, except for higher AST and bilirubin at diagnosis in the first group (Supplementary Table 3). The post-vaccination biopsy of the patient who progressed to LT showed lobular hepatitis with confluent necrosis and eosinophils. At LT, his liver showed post-necrotic stromal collapse, nodular transformation of the residual parenchyma and mild persistent lobular hepatitis.

      3.3 Autoantibodies

      Local testing

      A broad variety of autoantibody assays including IFT on rodent tissue sections and/or HEp2 cells as well as ELISAs were used in the participating centers, leading to inhomogeneous results difficult to compare (Table 1). Nuclear IFT on HEp2 cells was positive in most tested patients, being ≥1:160 in two thirds, the staining pattern being mostly homogeneous or fine speckled/speckled (Table 1). Anti-smooth muscle antibody (SMA) was detected in one third of the tested patients, with titers ≥1:160 in half of them. The IFT pattern on kidney tissue was not available. LKM, tested in 52 cases, was detected in four with a titer of 1:160 in all (Table 1). Anti-liver cytosol antibody was negative in all 32 patients tested. SLA was negative in all 45 tested cases. AMA was detected by IFT in five patients, four of whom had a titer ≥1:160. In one case, AMA, not tested by IFT, was positive by molecular testing.

      Centralized testing (Table 3)

      Serum samples for centralized and standardized autoantibody testing were available for 31/59 patients (52%) (Table 3). Two patients were negative for all tested specificities. ANA, tested by IFT on triple tissue, was present in three quarters, most of whom having titers >1:160. ANA by HEp2 cells was positive in 27 (87%), with mostly a fine speckled staining pattern. Anti-SMA was present in 19 patients, with titers ≥1:160 in 11, half having an isolated vessel pattern (V) and one third having a vessel, glomerulus and tubule pattern (VGT) on kidney sections. AMA was present in four patients by IFT (titers ≥1:160 in all), confirmed by molecular assay in all. LKM was found in four patients with moderate to high titers (1:80-1:160) in IFT, but without specificity for LKM-1, 2 or 3 by Western blot; one was positive for LKM-1 by LIA. PCA was positive in eight cases. Twenty patients had more than one autoantibody. Polyreactive IgG with reactivity against BSA/HIP1R was detected in almost half of the patients
      • Taubert R.
      • Engel B.
      • Diestelhorst J.
      • Hupa-Breier K.L.
      • Behrendt P.
      • Baerlecken N.T.
      • et al.
      Quantification of polyreactive immunoglobulin G facilitates the diagnosis of autoimmune hepatitis.
      .
      Table 3Centralized autoantibody testing in 31 patients with liver injury after vaccination against SARS-CoV-2.
      n%
      ANA on triple tissuepositive2374
      ANA titers on triple tissue80417
      ≥1601956
      ANA on HEp2cellspositive2787
      ANA titers on HEp2 cells80622
      ≥1602168
      ANA patterns on HEp2 cellshomogeneous415
      fine speckled1556
      nucleolar415
      centromere14
      mixed patterns311
      SMApositive1961
      SMA titer80842
      ≥1601135
      SMA patternV1053
      VGT737
      AMApositive413
      AMA titer≥1604
      LKMpositive413
      LKM titer801
      1603
      Western blotpositive for LKM1, LKM2, LKM30
      PCA

      PCA titer
      positive826
      802
      ≥1606
      Liver LIApositive516
      Liver LIALKM11
      AMA M24
      pIgG (cut-off = 1,27)positive1346.4
      pIgG (normalized arbitrary units)median (range)1.2 (0.7- 2.7)
      SARS-CoV-2, Severe Acute Respiratory Coronavirus 2; ANA, anti-nuclear antibody; LKM, liver kidney microsomal; AMA, anti-mitochondrial antibody; SMA, anti-smooth muscle antibody; V, vessel; VGT, vessel, glomerulus; tubule; SLA, soluble liver antigen; pIgG, polyreactive immunoglobulin G; PCA, parietal cell antibody.

      3.4 Treatment and outcome

      The treatment decision was made at each center according to local standards without a unified protocol. Most patients received immunosuppression (Table 1). Two patients were treated after five and seven months from initial diagnosis because of relapse after spontaneous remission. Therapy was initiated with steroids in all cases with a median equivalent dose of 50 mg prednisolone per day (range: 10-625 mg/day); four patients received ≥100 mg prednisolone-equivalent/day intravenously due to severe presentation with high bilirubin (> 10x ULN). Nine patients were started on treatment before undergoing liver biopsy, at a median time of 28 days, range 1-107. Various treatment schedules were used, including prednisone (n=18), prednisolone (n=16), meprednisone (n=8), methylprednisolone (n=5), prednisolone + azathioprine (n=6), and budesonide (6mg/day) + azathioprine (n=1).
      Liver tests improved after three months in all patients (Figure 2). There were no significant differences between treated and untreated subjects in term of demographics and clinical characteristics, vaccine type, time from vaccination to liver injury, histological and serological features, and outcome. ALT at three months after the onset of liver injury was normal in 24/58 patients (one patient died of cardiac decompensation two months after the onset of liver injury); six months data, available for 46 patients (80%), showed normal ALT levels in 30 patients (64%), of whom 23 were still on treatment. The three patients on long-term immunosuppression before vaccination were treated with steroids; two are still on treatment without complete ALT normalization after three months, and one could discontinue steroids after five months without relapse. At submission of this manuscript 14/59 (24%) patients were in remission without immunosuppression (five after spontaneous remission, nine after successful immunosuppression withdrawal), 23/59 (39%) were in remission during immunosuppression withdrawal, 12/59 (20%) experienced a decrease of transaminase levels without normalization on immunosuppression, 6/59 (10%) underwent a relapse after remission (two after spontaneous remission, four during immunosuppression weaning). One patient needed a LT, three (5%) died of non-liver related causes, of whom one of cardiac decompensation, and one, who had undergone remission and successful immunosuppression withdrawal, of progression of pre-existing extrahepatic cancer; a 77-year old lady, without pre-existing conditions, died of pulmonal and cerebral aspergillosis while on immunosuppressive treatment; the initial prednisone dose was 60 mg/day. All patients with fatal outcome or requiring LT were initially treated. The only patient with established cirrhosis responded well to steroid treatment, but relapsed after treatment discontinuation.

      3.5 Subgroup analyses

      The total cohort was heterogeneous in several aspects including co-medication, type of SARS-CoV-2 vaccine, time point of diagnosis of liver injury in the vaccination sequence, and presence of advanced liver fibrosis.

      Time of liver injury

      Patients in whom liver injury was diagnosed after the first vaccination exhibited less severe ALT elevation (median 17.8 ULN vs. 26.5 ULN, p=0.012) but higher IgG levels (median 19.0 g/l vs 16.5 g/l, p=0.026), with a higher frequency of SMA positivity at central testing (8/8 vs 12/23, p= 0.015) as compared to patients in whom the liver injury manifested after a second or third vaccination. Twenty patients presented with acute liver injury after the first vaccine dose, of whom 10 received a vectorial vaccine; in contrast, out of the 39 patients presenting with acute liver injury after the second or third vaccine dose, only six received a vectorial vaccine (p=0.006). Although patients with liver injury after the first or the second/third vaccination were treated with the same frequency and with comparable initial steroid doses and had comparable outcome at six months, AST levels were slightly higher at three months (1.4 ULN vs 0.9 ULN, p=0.051) and bilirubin was slightly higher (0.6 ULN vs 0.4 ULN, p=0.07) at six months follow-up in those who develop liver injury after the first dose.

      Type of vaccine

      Patients with liver injury after mRNA vaccines had higher transaminase levels (ALT 26.2 xULN vs 14.0 xULN, p=0.003; AST 25.1 xULN vs 11.2 × ULN, p=0.008) and higher impairment of coagulation (INR 1.3 vs 1.1, p=0.012) than those who developed hepatitis after vector vaccines. Treatment and treatment response were similar in both groups. A comparison between the two mRNA vaccines was limited by the small patient numbers. Nonetheless, patients with hepatitis after mRNA-1273 (n=12) had more severe histological injury (Ishak necro-inflammation grade 11 vs 9, p=0.001), higher SMA titers (≥1:160 in 8/8 vs in 2/8, p=0.007) and higher pIgG concentrations (median 1.6 vs 0.9, p=0.012) than after BNT162b2 (n=30). The comparison between the two vector vaccines AZD1222 (n=11) and Gam-COVID-Vac (n=5) did not show differences between these two small cohorts (data not shown).

      Advanced liver fibrosis

      The absence of advanced liver fibrosis in the work-up of an acute liver injury suggests drug-induced liver injury (DILI) or AIH-like DILI as more probable than AIH
      European Association for the Study of the Liver
      Electronic address: [email protected], Clinical Practice Guideline Panel: Chair:, Panel members, EASL Governing Board representative: EASL Clinical Practice Guidelines: Drug-induced liver injury.
      . Therefore, the liver histological injuries after SARS-CoV-2 vaccines were compared regarding the absence (n=52) or presence (n=7) of advanced liver fibrosis (defined as ≥ Ishak F3). F3 was used as a threshold as portal expansion in acute hepatitis is potentially interpreted as F1 or F2. There were no significant differences in the liver enzyme elevation, IgG levels, bilirubin, or INR at presentation (Supplementary Table 4). Treatment, liver function tests at 3 and 6 months and the overall comparison of the outcome was not significantly different between the two fibrosis groups. However, this comparison is limited by the small number of patients with advanced fibrosis.

      3.6 Rechallenge

      Fifteen patients were re-exposed to a SARS-CoV-2 vaccine after the diagnosis of hepatitis (Table 4).
      Table 4Re-challenge
      Patient IDSexAgeTime from hepatitis to re-exposure (days)Vaccine(s) prior to hepatitisVaccine(s) after hepatitisImmunosuppression at time of re-exposureOutcome after re-exposure
      Homologous vaccination
      9F67195Gam-COVID-Vac (sputnik adenovirus)ChAdOx1 (astrazeneca adenovirus)Yes (prednisone 6 mg/d + azathioprine 75 mg/d)No relapse
      11F63134Gam-COVID-VacChAdOx1Yes (meprednisone)No relapse
      16F4660ChAdOx1ChAdOx1Yes (prednisone)No relapse
      17M7255ChAdOx1ChAdOx1Yes (prednisone)No relapse
      2M5134mRNA-1273mRNA-1273NoNo relapse
      12F75128Gam-COVID-VacGam-COVID-VacYes (prednisone 25 mg/d)Re-exposure while still high transaminases without worsening
      18M5325BNT162b2BNT162b2Yes (prednisone 16 mg/d)Relapse, finally requiring liver transplantation
      20F6116ChAdOx1ChAdOx1NoRelapse, treated successfully with steroids (no treatment of first episode)
      7M782mRNA-1273mRNA-1273NoRelapse, treated successfully with steroids (no treatment of first episode) (Ad26.COV2.S 6 months later without relapse on prednisone 5 mg/d)
      19M6221BNT162b2BNT162b2NoRe-exposure while still high transaminases without steroids, improvement but no remission on prednisone+azathioprine
      Heterologous vaccination
      17M63181mRNA-1273Ad26.COV2.S (adenovirus)

      (2 doses 4 months apart)
      Yes (prednisone 5 mg/d)No relapse
      13F6899ChAdOx1BNT162b2Yes (prednisone and azathioprine)No relapse
      57F52426BNT162b2NVX-CoV2373 (recombinant)Yes (prednisone 5 mg/d)No relapse
      14M3392ChAdOx1BNT162b2NoNo relapse
      15F5866ChAdOx1BNT162b2NoRe-exposure while still high transaminases, treated successfully with steroids
      Ten received the same vaccine class, of whom six had no relapse (five on and one off immunosuppression), three relapsed (one on and two off immunosuppression), and one was re-vaccinated while transaminase levels were still elevated and showed improvement upon subsequent corticosteroid treatment. The patient who relapsed despite treatment finally needed a LT.
      Five patients were re-exposed to a different vaccine class (heterologous vaccination), of whom four had no relapse (three on and one off immunosuppression), and one, off immunosuppression at the time of re-vaccination, was re-exposed while transaminases were still elevated and responded well to steroids.
      When patients were grouped according to revaccination with or without ongoing immunosuppression, of those with ongoing immunosuppression 8/10 had no relapse or worsening of liver injury upon re-vaccination, one relapsed and one was vaccinated while elevated liver enzymes were still present. Of those without immunosuppression, 3/6 had no relapse, 1/6 had a relapse and 2/6 were revaccinated while elevated liver enzymes were still present.
      In summary, only one patient, who was rechallenged with the BNT162b2 vaccine, did relapse on immunosuppression, finally requiring a LT, and none of the four patients who have been rechallenged with heterologous vaccination while on remission (three on low-dose immunosuppression) did relapse.

      4. Discussion

      To date, most reports of acute liver injury diagnosed after SARS-CoV-2 vaccines refer to single cases or small patient cohorts, except for a recent multicenter study by Efe et al, which aimed at assessing the clinical characteristics and outcome of hepatitis occurring after SARS-CoV-2 vaccines irrespective of a previous history of liver disease

      Efe C, Kulkarni AV, Beretta-Piccoli BT, Magro B, Stättermayer AF, Cengiz M, et al. Liver injury after SARS-CoV-2 vaccination: Features of immune-mediated hepatitis, role of corticosteroid therapy and outcome. Hepatology [Internet]. [cited 2022 May 14];n/a. Available from: https://onlinelibrary.wiley.com/doi/abs/10.1002/hep.32572.

      . The present study focuses on centralized rigorous liver histology evaluation of patients without pre-existing liver conditions, to evaluate whether post-SARS-CoV-2 vaccination liver injury has specific features and can be distinguished from other acute onset hepatitides.
      Liver histology showed a picture of predominant lobular hepatitis in three quarters of the cases, while predominant portal hepatitis was present in fewer than 1/5 of patients, supporting an acute onset of liver injury. Almost all patients in the present cohort were seropositive locally and at centralized testing for autoantibodies associated with AIH, frequently at high titers, and had high IgG, collectively suggesting a diagnosis of AIH or AIH-like drug-induced liver disease (DILI)
      • Castiella A.
      • Zapata E.
      • Lucena M.I.
      • Andrade R.J.
      Drug-induced autoimmune liver disease: A diagnostic dilemma of an increasingly reported disease.
      . The fact that only few of them had advanced liver fibrosis, would support that elevation of transaminase levels following SARS-CoV-2 vaccination reflects acute liver injury in absence of preexisting unrecognized chronic liver damage, and therefore would favor AIH-like DILI. For those patients with established fibrosis, SARS-CoV-2 vaccination may have unmasked pre-existing undiagnosed chronic liver disease, including AIH. Of note, the majority of the patients presented after the second vaccine dose, suggesting that repeated exposure increases the risk of liver injury with autoimmune features, an observation reported also in DILI
      • Lucena M.I.
      • Kaplowitz N.
      • Hallal H.
      • Castiella A.
      • García-Bengoechea M.
      • Otazua P.
      • et al.
      Recurrent drug-induced liver injury (DILI) with different drugs in the Spanish Registry: the dilemma of the relationship to autoimmune hepatitis.
      . Some patients might have had subclinical liver inflammation after the first dose, which may explain the presence of liver fibrosis despite clinically acute presentation.
      Criteria for differentiating classical AIH from AIH-like DILI are a matter of ongoing discussion: while AIH is characterized by long-term immunosuppression dependency and frequent presence of advanced fibrosis at diagnosis, the latter is characterized by a low relapse rate after withdrawal of a short-term steroid course
      European Association for the Study of the Liver
      Electronic address: [email protected], Clinical Practice Guideline Panel: Chair:, Panel members, EASL Governing Board representative: EASL Clinical Practice Guidelines: Drug-induced liver injury.
      . Ninety-two percent of our patients were treated with steroids, with or without azathioprine, and showed an excellent response, liver enzymes improving in all cases and normalizing in two thirds after 6 months; however, as most of them are still on immunosuppression and the cohort follow up is too short, it is impossible to determine whether they suffer from AIH-like DILI or classical AIH purely based on their response to treatment. In an attempt to evaluate whether published scoring systems could help in the differential diagnosis, we have applied both the simplified IAIHG diagnostic scoring system
      • Hennes E.M.
      • Zeniya M.
      • Czaja A.J.
      • Parés A.
      • Dalekos G.N.
      • Krawitt E.L.
      • et al.
      Simplified criteria for the diagnosis of autoimmune hepatitis.
      and the newly proposed ERN histological criteria
      • Lohse A.W.
      • Sebode M.
      • Bhathal P.S.
      • Clouston A.D.
      • Dienes H.P.
      • Jain D.
      • et al.
      Consensus Recommendations for Histological Criteria of Autoimmune Hepatitis from the International AIH Pathology Group.
      . Neither provided helpful information, as 82% of patients scored as ‘typical or ‘probable’ AIH in the IAIHG diagnostic system and 92% of patients as ‘likely’ or ‘possible’ AIH in the ERN histology system. In particular, the new ERN histological criteria, which include the acute presentation of AIH characterized by lobular hepatitis, led to a more frequent rate of AIH likelihood (“likely”, 70%) compared to the IAIHG criteria (“typical”, 24%)
      • Mieli-Vergani G.
      • Zen Y.
      • Vergani D.
      Reassessement of the histological features of autoimmune hepatitis.
      . This observation confirms that the diagnosis of AIH and the differential diagnosis with AIH-like DILI cannot be based solely on histology but requires a collegial approach to the clinical and laboratory findings. To evaluate the differential diagnostic role of pIgG, a new serological marker for AIH with a reported higher specificity and accuracy than conventional autoantibodies
      • Taubert R.
      • Engel B.
      • Diestelhorst J.
      • Hupa-Breier K.L.
      • Behrendt P.
      • Baerlecken N.T.
      • et al.
      Quantification of polyreactive immunoglobulin G facilitates the diagnosis of autoimmune hepatitis.
      , we have tested our cohort and found pIgG less frequently than ANA and SMA. The follow-up of our cases and future studies are necessary to establish whether pIgG have a role in distinguishing AIH-like DILI from classical AIH with an acute presentation.
      The question as to whether vaccines can trigger autoimmunity predates the COVID-19 pandemic. A meta-analysis addressing this question published in early 2020 could not find an increased incidence of autoimmune diseases in vaccinated people
      • Petráš M.
      • Lesná I.K.
      • Dáňová J.
      • Čelko A.M.
      Can Vaccination Trigger Autoimmune Disorders? A Meta-Analysis.
      . Likewise, the current notion is that vaccines are not associated with flares of autoimmune diseases: in contrast, they rather prevent flares caused by vaccine-preventable infections
      • Wagner N.
      • Assmus F.
      • Arendt G.
      • Baum E.
      • Baumann U.
      • Bogdan C.
      • et al.
      Impfen bei Immundefizienz: Anwendungshinweise zu den von der Ständigen Impfkommission empfohlenen Impfungen. (IV) Impfen bei Autoimmunkrankheiten, bei anderen chronisch-entzündlichen Erkrankungen und unter immunmodulatorischer Therapie.
      . Nonetheless, de-novo manifestations or aggravations of a variety of autoimmune diseases have been reported after different SARS-CoV-2 vaccinations
      • Chen Y.
      • Xu Z.
      • Wang P.
      • Li X.-M.
      • Shuai Z.-W.
      • Ye D.-Q.
      • et al.
      New-onset autoimmune phenomena post-COVID-19 vaccination.
      .
      The overall similar phenotype of hepatitis occurring after mRNA or vectorial vaccines observed in this study may suggest that the liver injury is related to the spike protein antigen itself, rather than to a non-antigen specific immune-mediated damage, as reported by a recent case study
      • Boettler T.
      • Csernalabics B.
      • Salié H.
      • Luxenburger H.
      • Wischer L.
      • Alizei E.S.
      • et al.
      SARS-CoV-2 vaccination can elicit a CD8 T-cell dominant hepatitis.
      .
      Most patients in the present cohort responded well to steroid-based therapy, though it is unknown how many would have improved spontaneously. Only one patient required LT for severe deterioration of liver injury after re-exposure to the same SARS-CoV-2 vaccine. It is of interest that of the 15 patients in our cohort who were re-exposed to vaccination, only three relapsed, all re-vaccinated with the same vaccine type.
      Liver disease was not the cause of death of the three patients who died, but it is of concern that one of them had invasive pulmonary and cerebral aspergillosis in association with steroid treatment. As some two thirds of patients in biochemical remission are still under immunosuppressive therapy at six months, longer follow up is warranted to evaluate whether immunosuppression has indeed a beneficial effect on the prognosis of liver injury associated with SARS-CoV-2 vaccine.
      The study of the pathogenic mechanisms in autoimmune disease is hampered by the inability to assess early events. The appearance of a liver autoimmune profile compatible with AIH shortly after the administration of anti-SARS-CoV-2 vaccine offers the opportunity of investigating the unfolding events leading to liver autoimmunity by investigating its early stages, including virus/self cross-reactivity, maturation of the autoimmune response, and epitope spreading both at the T and B cell level.
      The limitations of this multicenter study include reporting and selection bias. Subjects were recruited mostly via networks focused on autoimmune as well as rare liver diseases and the contributing centers were mostly tertiary referral centers. The inclusion criteria of a liver biopsy might have caused a bias towards more severe and not rapidly self-limiting liver injuries. This is highlighted by the high treatment rate of 92% in the current study compared to a recently published multicenter cohort, in which only half of the patients had a liver biopsy and received immunosuppressive therapy

      Efe C, Kulkarni AV, Beretta-Piccoli BT, Magro B, Stättermayer AF, Cengiz M, et al. Liver injury after SARS-CoV-2 vaccination: Features of immune-mediated hepatitis, role of corticosteroid therapy and outcome. Hepatology [Internet]. [cited 2022 May 14];n/a. Available from: https://onlinelibrary.wiley.com/doi/abs/10.1002/hep.32572.

      . Both studies are large cooperative efforts, demonstrating that the condition is rare.
      Our study gives no estimate of the incidence of liver injury after SARS-CoV-2 vaccination. When a high proportion of the world population is vaccinated within a few months, rare diseases - including AIH or AIH-like DILI due to other drugs - will be diagnosed close to a SARS-CoV-2 vaccination just by chance without any causal relationship. In contrast, flares or new onset of autoimmune diseases not associated with SARS-CoV-2 vaccines may not be recognized and reported with the same attention. Moreover, the occurrence of liver disease during the coronavirus pandemic can be underestimated owing to the overload of the health care systems and to patient restraint in seeking medical attention. This might explain the reduced rate of newly diagnosed AIH during the pandemic in a tertiary referral center in Germany
      • Rüther D.F.
      • Weltzsch J.P.
      • Schramm C.
      • Sebode M.
      • Lohse A.W.
      Autoimmune hepatitis and COVID-19: No increased risk for AIH after vaccination but reduced care.
      .
      The present study cannot prove or refute a causal relationship between SARS-CoV-2 vaccines and liver injury with autoimmune features. As most patients received other drugs during the three months preceding liver injury, other DILI triggers cannot be excluded.
      In conclusion, acute liver injury with autoimmune features with temporal association with SARS-CoV-2 vaccination is likely to be a heterogeneous condition requiring a thorough work-up and careful follow-up. Patients are often treated with immunosuppression, with a good short-term response, though firm indications on when to start immunosuppression are needed, to avoid adverse effects. This study does not justify withholding SARS-CoV-2 vaccination, which has proven benefits by preventing severe COVID-19 disease and death of millions of people.

      Conflict of interest statement

      The authors do not have any conflict of interest pertaining to this study. Please refer to the accompanying ICMJE disclosure forms for further details.

      Authors’ contributions

      All authors made substantial contributions to the conceptualization and design, the analysis, and data interpretation. BTBP and RT: conceptualization and supervision of the study, data interpretation, drafting of the manuscript, review and editing of the manuscript. GC, TK: data collection, data interpretation and statistical analysis. YZ: review of histological slides. AC, HW, DV, GMV, MIL, RJA: critical revision of the manuscript. BE, AMV, CE, AFS, JPW, MS, CB, AL, TJG, LK, AC, JP, EDM, IB, TDS, FP, FI, PDP, TB, MK, NS, FB, BG, GP, MU, HJ, GÖE, NKS: data collection. All authors have approved the final version of the manuscript.

      Financial support

      The authors received no financial support to produce this manuscript.

      Data availability statement

      The row data are available upon motivated request to the corresponding author.

      Acknowledgments

      We thank Stephanie Loges and Nicole Henjes from the autoantibody laboratory of Hannover Medical School for centralized autoantibody assessment. We also thank Cathrine Guettier from Hépatologie et Transplantation Hépatique, Hôpital Paul Brousse for handling the liver biopsies.

      Appendix A. Supplementary data

      The following is/are the supplementary data to this article:

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