Henoch-Schönlein purpura following influenza vaccinations during the pandemic of influenza A (H1N1).

Although the etiology of Henoch-Schönlein purpura (HSP) remains unclear, influenza vaccinations have been implicated as possible triggers for HSP. We describe four patients with HSP following influenza vaccinations which developed during the pandemic of influenza A (H1N1) 2009 and review the literature concerning HSP associated with this vaccine. HSP in patients developed in October and November, 2009. Four patients exhibited purpura, three patients complained of arthralgias, and one patient had both abdominal pains and renal involvement. Reviewing the literature, 11 patients with HSP following influenza vaccinations have been reported. Eight patients were children and five patients had past histories of immunologically mediated diseases including HSP, drug eruptions, and food allergy. While a favorable outcome was noted in most patients, one patient developed end-stage renal failure and another patient exhibited chronic glomerulonephritis. Although the precise reason for clustering of our patients with HSP following influenza vaccination was unclear, increasing use of the recent influenza vaccine associated with the pandemic of influenza A (H1N1) 2009 might explain this phenomenon. Because the incidence of HSP caused by influenza vaccination was very low, influenza vaccination should not be limited for this reason. However, caution may be required with its use in children with immunologically mediated diseases such as HSP.