Underreporting of the 5-year tetanus, diphtheria, pertussis and polio booster vaccination in the Danish Vaccination Register

Table 3 Corrected vaccination coverages for children living in Copenhagen born in 2010

	Vaccination coverage considering non-participants as not vaccinated
	Vaccination coverage in the study, % (95% CI)		Corrected vaccination coverage among children in Copenhagen born in 2010, % (95% CI)
Documented vaccination^a	128/692	18% (16, 22%)	0.89^b + (1–0.89) × 0.18	91% (90, 91%)
Answered ‘yes’ to vaccination	186/692	27% (23, 31%)	0.89^b + (1–0.89) × 0.27	92% (91, 92%)
	Vaccination coverage considering non-participants as vaccinated at the same rate as participants
	Vaccination coverage in the study, % (95% CI)		Corrected vaccination coverage among children in Copenhagen born in 2010, % (95% CI)
Documented vaccination^a	128/340	38% (31, 46%)	0.89^b + (1–0.89) × 0.38	93% (92, 94%)
Answered ‘yes’ to vaccination	186/340	55% (46, 65%)	0.89^b + (1–0.89) × 0.55	95% (94, 96%)

^a A vaccination was considered documented if the parents could provide a date of vaccination from a vaccination card or equivalent written documentation or if the parents had the vaccination confirmed by their general practitioner
^b Vaccination coverage in the DDV = 5347/6039 (89%)

ISSN: 1471-2458