Additional Evidence on Serological Correlates of Protection against Measles: An Observational Cohort Study among Once Vaccinated Children Exposed to Measles oleh Tom Woudenberg, Rob van Binnendijk, Irene Veldhuijzen, Frits Woonink, Helma Ruijs, Fiona van der Klis, Jeroen Kerkhof, Hester de Melker, Rik de Swart, Susan Hahné