Compared with mild to moderate disease, patients with severe HAVID had more often a systolic blood pressure < 100 mmHg on admission (OR = 3.10; 95% CI: 1.35–7.14; p = 0.004), abdominal symptoms, especially vomiting (OR = 2.02; 95% CI: 1.05–3.90; p = 0.018), leucocytosis (OR = 2.53; 95% CI: 1.34–4.78; p = 0.002), thrombocytopaenia (OR = 7.24; 95% CI: 0.96–54.69; p = 0.028), elevated urea levels (OR = 2.03; 95% CI: 1.04–3.95; p = 0.018) and CRP values ≥ 20 times above reference values (n = 23). Here, CRP is linked to Thrombocytopenia.