Study subjects
Patients with a documented clinical history of fish allergy (n=263) were recruited from six countries (Austria, China, Denmark, Luxembourg, Norway and Spain). Their demographic and clinical characteristics are summarized in Table I and detailed in Table SI . Sensitization to fish was confirmed by ImmunoCAP (ThermoFisher Scientific), skin prick tests (SPT) to fish extracts and/or prick-to-prick test (PPT) to fresh fish for 255 patients. Total IgE measured by ALEX2 (MacroArray Disgnostics) and ImmunoCAP demonstrated a significant positive correlation (Spearman’s Rho=0.88) (Figure S1 ). Fish allergy symptoms’ severities were scored from 1 to 4 (Table 1) . Anaphylaxis scoring was performed according to Ring et al.14 Distribution of age groups and sex among the participants from each country is shown inFigure S2 .
Informed written consent was obtained from all participants or their legal representatives and the study was approved by the Ethics Committees of the participating institutions: Austria- Ethics Committee of the city of Vienna (EK-12-126-0712); China- Joint CUHK-NTEC CREC (2017.542); Denmark- (S-20210170); Luxembourg- CNER approval (201307/04); Norway- REK (2013/ 757); Spain- Hospital Clínic de Barcelona (HCB/2021/1129) and Hospital Sant Joan de Déu, Esplugues de Llobregat (PIC-97-20).