Michael Hahn, Paul Schnitzler, Brunhilde Schweiger, Christina Kunz, Anthony D. Ho, Hartmut Goldschmidt, Michael Schmitt. Efficacy of single versus boost vaccination against influenza virus in patients with multiple myeloma. Haematologica 2015;100(7):e285-e288; https://doi.org/10.3324/haematol.2014.116772.