Influenza outbreaks in nursing homes with high vaccination coverage in Navarre, Spain, 2011/12 Castilla, J and Cía, F and Zubicoa, J and Reina, G and Martínez-Artola, V and Ezpeleta, C, Eurosurveillance, 17, 20141 (2012), https://doi.org/10.2807/ese.17.14.20141-en