Timeliness of DTaP-IPV-Hib Vaccination and Development of Atopic Dermatitis Between 4 Months and 1 Year of Age—Register-Based Cohort Study

Background An Australian study including 4433 children found that delayed Diphtheria-Tetanus-acellular Pertussis–containing vaccination was associated with reduced risk of developing atopic dermatitis (AD) before age 1 year. Objective We assessed whether against diphtheria, tetanus, acellular pertussis, polio, and Haemophilus influenzae type b (Diphtheria, Tetanus, Pertussis – Inactivated Polio vaccine [DTaP]) a new cases AD year in Denmark. Methods used nationwide registers to follow 883,160 born Denmark from 1997 2012. Binary regression models adjusting for potential confounding factors were applied estimate relative risks (adjusted [aRRs]) among DTaP (defined as given month or more after the recommended age) compared timely vaccinated children. Results Among 143,429 first dose DTaP, 4,847 (3.4%) developed between 4 months year, 27,628 (3.7%) 739,731 not having (aRR 0.94; 95% CI, 0.91-0.97). The aRR 0.94 (95% 0.90-0.99) second dose, 0.88 0.82-0.93) when comparing doses all Conclusions results support hypothesis is months. dose-dependent relationship strengthens evidence causal relationship. Some countries are introducing maternal pertussis delaying providing possibility further testing hypothesis.