Published online: October 1, 2020
Atopic dermatitis, also called eczema, is the most common skin disease in high income countries, affecting up to 25% of children. Atopic dermatitis begins in the first year of life for most children.
Vaccines are one of the first medical interventions received in infancy. Vaccines may have non-specific effects that affect susceptibility towards other conditions, in addition to protection against the vaccine-targeted infections. The timing of vaccination might influence these non-specific effects. The timing of effective routine infant vaccinations differs across countries and it is relevant to determine if this timing influences the development of atopic dermatitis.
In The Journal of Allergy and Clinical Immunology: In Practice, Gehrt et al. published the results of a study investigating if the timing of vaccination with the non-live vaccine against diphtheria, tetanus, pertussis, polio, and Haemophilus Influenzae type b (abbreviated DTaP-IPV-Hib) was associated with the development of atopic dermatitis. The study included almost 900,000 children born in Denmark from 1997 to 2012 who were recommended to get 3 doses of DTaP-IPV-Hib at 3, 5, and 12 months of age. However, more than 16 % of the children got the first dose of DTaP-IPV-Hib after 4 months of age, providing an opportunity to compare the timing of vaccination. The study used national health registries and defined atopic dermatitis based on an algorithm considering prescriptions and hospital coding of diagnoses, and cases were determined between 4 months and 1 year of age (those categorized as having atopic dermatitis before the recommended age of vaccination were excluded).
Gehrt et al. found that delayed vaccination with the first dose of DTaP-IPV-Hib by more than 1 month was associated with a 6% lower risk of developing atopic dermatitis. This corresponds to a reduction of 1 case of atopic dermatitis for every 281 infants with delayed vaccination. The effect was more pronounced among children from families from the lowest household income. In a post hoc analysis, delayed vaccination with both the first and second dose of DTaP-IPV-Hib was associated with 12% lower risk of developing atopic dermatitis between 6 months and 1 year of age. The association was stronger for girls than boys.
The results suggest that timing of routine childhood vaccinations may be one of many factors influencing development or severity of atopic dermatitis. The authors point out that many countries start using pertussis vaccination in pregnancy, accompanied with fewer and later DTaP-IPV-Hib vaccinations for the child, offering a further opportunity to explore this relationship to outcomes of atopic dermatitis.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.