The Danish Civil Registration System (CRS) was established in 1968, where all persons alive and living in Denmark were registered. Among many other variables, it includes individual information on personal identification number, gender, date of birth, place of birth, place of residence, citizenship, continuously updated information on vital status, and the identity of parents and spouses. To evaluate the quality and completeness of the information recorded on persons in the CRS, we considered all persons registered on November 4, 2005, i.e. all persons who were alive and resident in Denmark at least one day from April 2, 1968 to November 4, 2005, or in Greenland from May 1, 1972 to November 4, 2005. A total of 8,176,097 persons were registered. On November 4, 2005, 5,427,687 (66.4%) were alive and resident in Denmark, 56,920 (0.7%) were alive and resident in Greenland, 2,141,373 (26.2%) were dead, 21,160 (0.3%) had disappeared, and 528,957 (6.5%) had emigrated. Among persons born in Denmark 1960 or later the CRS contains complete information on maternal identity. Among persons born in Denmark 1970 or later the CRS contains complete information on paternal identity. Among women born in Denmark April 1935 or later the CRS contains complete information on all their children. Among males born in Denmark April 1945 or later the CRS contains complete information on all their children. The CRS contains complete information on: a) immigrations and emigrations from 1971 onwards, b) permanent residence in a Danish municipality from 1971 onwards, c) permanent residence in a municipality in Greenland from May 1972 onwards, and d) full address in Denmark from 1977 onwards. Data from the CRS is an important research tool in epidemiological research, which enables Danish researchers to carry out representative population-based studies on e.g. the potential clustering of disease and death in families and the potential association between residence and disease and death.

Background A critical factor shaping parental attitudes to vaccination is the parent’s interactions with health professionals. An effective interaction can address the concerns of vaccine supportive parents and motivate a hesitant parent towards vaccine acceptance. Poor communication can contribute to rejection of vaccinations or dissatisfaction with care. We sought to provide a framework for health professionals when communicating with parents about vaccination. Methods Literature review to identify a spectrum of parent attitudes or ‘positions’ on childhood vaccination with estimates of the proportion of each group based on population studies. Development of a framework related to each parental position with determination of key indicators, goals and strategies based on communication science, motivational interviewing and valid consent principles. Results Five distinct parental groups were identified: the ‘unquestioning acceptor’ (30–40%), the ‘cautious acceptor’ (25–35%); the ‘hesitant’ (20–30%); the ‘late or selective vaccinator’ (2–27%); and the ‘refuser’ of all vaccines (<2%). The goals of the encounter with each group will vary, depending on the parents’ readiness to vaccinate. In all encounters, health professionals should build rapport, accept questions and concerns, and facilitate valid consent. For the hesitant, late or selective vaccinators, or refusers, strategies should include use of a guiding style and eliciting the parent’s own motivations to vaccinate while, avoiding excessive persuasion and adversarial debates. It may be necessary to book another appointment or offer attendance at a specialised adverse events clinic. Good information resources should also be used. Conclusions Health professionals have a central role in maintaining public trust in vaccination, including addressing parents’ concerns. These recommendations are tailored to specific parental positions on vaccination and provide a structured approach to assist professionals. They advocate respectful interactions that aim to guide parents towards quality decisions.

In a Policy Forum, Peter Hotez and colleagues discuss vaccination exemptions in US states and possible consequences for infectious disease outbreaks.