Unexpected loss of contact allergy to aluminium induced by vaccine

Background. In studies in Gothenburg, Sweden, in the 1990s of an aluminium hydroxide‐adsorbed pertussis toxoid vaccine, 745 of ∼76 000 vaccinated children developed long‐lasting itchy subcutaneous nodules at the vaccination site. Of 495 children with itchy nodules patch tested for aluminium allergy, 376 (76%) were positive. Objectives. To study the prognosis of the vaccine‐induced aluminium allergy. Patients and methods. Two hundred and forty‐one children with demonstrated aluminium allergy in the previous study were patch tested again 5–9 years after the initial test, with the same procedure as used previously. Results. Contact allergy to aluminium was no longer demonstrable in 186 of the retested 241 children (77%). A negative test result was more common in children who no longer had itching at the vaccination site; it was also related to the age of the child, the time after the first aluminium‐adsorbed vaccine dose, and the strength of the reaction in the first test. Conclusions. Patch test reactivity to aluminium seems to disappear or weaken with time.