Two patterns of systemic immediate-type reactions to Japanese encephalitis vaccines.

We have found two different patterns of systemic immediate-type reactions to Japanese encephalitis vaccine containing gelatin as the stabilizer. One group of affected children had cutaneous and respiratory symptoms (e.g., systemic urticaria and wheezing) and the other group had cardiovascular symptoms (e.g., hypotension and cyanosis) without cutaneous and respiratory symptoms. The children in the former group had anti-gelatin IgE in their sera, whereas those in the latter group did not. We think that the two patterns may be caused by different mechanisms or different allergens.