Duration of Protection From Pneumonia After Pneumococcal Vaccination in Hemodialysis Patients (DOPPIO): Protocol for a Prospective Multicenter Study oleh Sibylle Mellinghoff, Gero von Gersdorff, Caroline Bruns, Kerstin Albus, Vassiliki Dimitriou, Angela Steinbach, Mathias Schaller, Jörg Janne Vehreschild, Oliver A Cornely, Blasius Janusch Liss