Adverse Reactions after Vaccination and Allergen-Specific Immunotherapy: Contact Allergy to Aluminium and Itching Nodules

The aim of the work presented in this thesis was to investigate two different types of adverse reactions, persistent itching nodules and contact allergy to aluminium, after immunization with aluminium-containing vaccines and aluminium-containing allergen extracts used for allergen-specific immunotherapy (ASIT).
The first paper describes active parental reporting of adverse events (AEFIs) after a booster dose of diphtheria-tetanus vaccine (DT). A parental questionnaire elicited reports of AEFIs within seven days of vaccination. A follow-up phone call was made in all cases of positive response. Active surveillance by parental reports was shown to be a useful complement to passive surveillance of childhood immunization.
The proportion of late local reactions after immunization with a fourth dose of DT vaccines containing different aluminium compounds as adjuvant was investigated in the second study, in which a prospective cluster-randomized, active surveillance study was performed in 25,232 10-year-olds. Parental reports were collected 6 months after vaccination. 3-6 children per 10,000 had a persistent itching nodule. Contact allergy to aluminium was not detected. These findings support the continued use of the vaccine presently offered in the Swedish vaccination programme. However, continued surveillance is warranted.
The study described in the third paper examined retrospectively whether ASIT could induce contact allergy to aluminium, and investigated a possible association between persistent subcutaneous nodules and aluminium allergy. The study consisted of a non-clinical part based on a questionnaire, and a clinical part involving a physical examination, self-assessment of itching, and patch testing. A statistically significant association was found between contact allergy to aluminium and persistent subcutaneous nodules in children given ASIT. Contact allergy was found in eight of the participants, all given ASIT.
The fourth paper presents the results of a prospective study on whether ASIT with allergen preparations containing aluminium hydroxide induces contact allergy to aluminium. The association between contact allergy to aluminium and persistent itching nodules was also studied. Three groups undergoing ASIT were patch tested with aluminium chloride hexahydrate before and during ASIT. A control group was included (untreated). At the end of the study all groups were patch tested. A high rate of contact allergy to aluminium was found. The study did not confirm or refute ASIT as a risk factor. Allergy to aluminium and itching nodules after ASIT seemed to be more common among children, and among those suffering from atopic dermatitis.