Epidemiology and outcome of invasive pneumococcal disease among adults in Belgium, 2009–2011 Verhaegen, J and Flamaing, J and De Backer, W and Delaere, B and Van Herck, K and Surmont, F and Van Laethem, Y and Van Damme, P and Peetermans, W, Eurosurveillance, 19, 20869 (2014), https://doi.org/10.2807/1560-7917.ES2014.19.31.20869