- SPT positive (mean wheal diameter ≥ 3mm compared to negative control; negative control should be negative; histamine control should be positive (mean wheal diameter ≥ 3mm)) patients to allergen(s) other than birch pollen, in the absence of a negative provocation test for this allergen(s) (within 1 year), who are expected to have clinically relevant symptoms during the birch pollen season