Influenza vaccination and chemotherapy: a shot in the dark?

Influenza infection is a potential cause of excess morbidity in patients who are immunosuppressed because of haemato-oncological malignancy or its treatment. Therefore vaccination against influenza is recommended in these patient groups. This systematic review of the literature and vaccine manafacturers' data assesses the current levels of knowledge concerning influenza vaccination in this patient group. There is a paucity of data, and the patient groups in the studies are heterogeneous. Serological responses are generally lower than expected in healthy controls and may be critically dependent on the timing of vaccination relative to chemotherapy. Antibody levels considered protective in healthy individuals may not prevent clinical infection in those with malignant disease. There are no data on protection from clinical infection. The vaccine appears to be well tolerated in this patient group. It is reasonable to offer vaccination to patients receiving treatment for haemato-oncological disorders. However, the degree of clinical protection afforded may be inferior to that experienced by healthy individuals. Further trials are warranted to assess the magnitude of benefit and optimal schedules of vaccination.