Table 5. Predictive value of self-reported history of disease and vaccination in paediatric healthcare workers, Denmark, 2019 (n = 555).

Disease		EIA positive	EIA negative	Total	PPV		NPV
		n	n	n	%	n/total	%	n/total
Measles
HD	Yes	200	3	203	98.5	200/203	15.8	36/228
	No	192	36	228
HV	Yes	233	34	267	87.3	233/267	1.3	2/155
	No	153	2	155
Mumps
HD	Yes	144	4	148	97.3	144/148	20.8	51/245
	No	194	51	245
HV	Yes	212	45	257	82.5	212/257	6.7	10/149
	No	139	10	149
Rubella
HD	Yes	180	6	186	96.8	180/186	11.3	25/222
	No	197	25	222
HV	Yes	251	27	278	90.3	251/278	2.8	4/145
	No	141	4	145
Varicella
HD	Yes	475	6	481	98.8	475/481	7.7	1/13
	No	12	1	13
HV	Yes	12	2	14	85.7	12/14	0.5	2/392
	No	390	2	392

EIA: enzyme immunoassay; HD: history of disease; HV: history of vaccination; NPV: negative predictive value; PPV: positive predictive value.

Subjects answering ‘unsure’ to a history of disease or vaccination were excluded from analysis.