Research question 1.b Among children with a timely 1st dose of DTaP-IPV-Hib (vaccination before 4 months of age), is delayed vaccination with the second dose of DTaP-IPV-Hib (vaccination at or after 6 months of age) associated with a reduced risk of development of atopic dermatitis from 6 months and until but not including 12 months of age compared with receiving the second dose of DTaP-IPV-Hib before 6 months of age?