RT Journal Article SR Electronic(1) A1 Heijnen, M. L.A. A1 Dorigo-Zetsma, J W A1 Bartelds, A I M A1 Wilbrink, B A1 Sprenger, M. J.W YR T1 JF VO OP UL https://www.eurosurveillance.org/content/10.2807/esm.04.07.00054-es