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.