Gehrt L, Rieckmann A, Kiraly N, et al. - This study was undertaken to determine if delayed vaccination against diphtheria, tetanus, acellular pertussis, polio, and Haemophilus influenzae type b (Diphtheria, Tetanus, acellular Pertussis – Inactivated Polio vaccine – Haemophilus influenzae type b [DTaP]) was correlated with a reduced risk of new cases of atopic dermatitis (AD) before age 1 year in Denmark. Nationwide registers were used to follow 883,160 children born in Denmark from 1997 to 2012. Four thousand eight hundred forty-seven (3.4%) of the 143,429 children with a delayed first dose of DTaP developed AD between age 4 months and 1 year, compared with 27,628 (3.7%) among 739,731 children not having delayed DTaP. The findings support the idea that delayed vaccination with DTaP is associated with decreased risk of developing new cases of AD after age 4 months. The dose-dependent relationship confirms the proof of a causal relationship. Some countries are implementing vaccination against maternal pertussis and delaying the first dose of DTaP, thereby offering a possibility for further testing of the hypothesis.