Does Timeliness of DTaP-IPV-Hib Vaccination Affect Development of Atopic Dermatitis Before 1 Year of Age?

It has been found that the non-live vaccine against Diphtheria, Tetanus, and Pertussis (DTP) in addition to its disease specific effects may have so called "non-specific effects" with the potential to affect sensitivity towards vaccine unrelated pathogens, resulting in excess mortality(Aaby, Kollmann, \& Benn, 2014). A recent study from Australia found that delayed vaccination with the first dose of Diphtheria, Tetanus, and acellular Pertussis(DTaP)-containing vaccine is associated with reduced risk of atopic dermatitis (aOR: 0.57; 95% CI: 0.34-0.97, P = 0.04) and reduced use of medication against atopic dermatitis (aOR: 0.45; 95% CI: 0.24-0.83, P = 0.01)(Kiraly et al., 2016). This register based observational study aims to extend the existing knowledge on non-specific effects of non-live vaccines by testing the above finding, that delayed vaccination with Diphtheria, Tetanus, acellular Pertussis - Inactivated Polio vaccine - Haemophilus influenzae type b (DTaP-IPV-Hib) is associated with lower risk of developing atopic dermatitis before 1 year of age in the Danish birth cohorts from 1997-2012.