Influenza Vaccination in Patients with Hematologic Malignancies: Analysis of Practices in 200 Patients in a Single Center

Vaccination against influenza in patients with hematologic malignancies has long been a matter of clinical uncertainty. Recent studies demonstrated the immunogenicity and the tolerance of the vaccine in this population and the absence of exacerbation of the hematologic disease after vaccination. However practices are still heterogeneous and there are no established routines in France regarding the influenza vaccination of these patients. The aim of this study was to analyse vaccinal practices in a single centre and to determine clinical efficiency of the vaccination. A standardized questionnaire about influenza vaccination was filled out by 200 patients with hematologic malignancies in January, 2008 and the patients were then observed prospectively during the epidemic season to May, 2008. The median age was 58.3 (range 18–87) ; 40% of patients were older than 65 y and could benefit from a free influenza vaccine after information by social security. Most patients suffered from lymphoid malignancies (diffuse large B-cell lymphoma: 30%; follicular, marginal, lymphoplasmacytic or mantle cell lymphoma: 31.5%; multiple myeloma: 13.5%; Hodgkin’s disease:13%). The treatment was ongoing in 53.5% of cases, using aplasia-inducing chemotherapy regimens in 27.5%, rituximab in 27.5% and/or steroids in 33.5%. One quarter of patients disclosed one or several comorbidities and 14.5% had a a past medical history of autologous stem cell transplantation. Lymphopenia was present in 34.9% of cases and hypogammaglobulinemia in 21.7%. Global vaccinal rate was 25.5%; it was 16.6% among patients younger than 65 y and 38.75% among those older than 65 y. The most frequent reasons for not being vaccinated were: the vaccination was not suggested to the patients (53.7%), vaccination was contraindicated by doctors (24.2%), the patient refused the vaccine (21.5%). The main reasons for physicians for contraindicating the vaccine were: hematologic malignancy could be worsened by vaccination (33.3%), the vaccination could generate illness or asthenia (27.8%), the vaccination could not be efficient under chemotherapy (16.7%), unknown (22.2%). Half of patients who refused the vaccine were afraid of having fever; 15.5% refused because they thought that the vaccine was uselessness. Thirteen patients (6.7%) developed influenza during follow-up and 38 (19.5%) presented a significant pulmonary infection. We did not establish a significant link between the vaccination and a protection against influenza, even in specific subgroups of patients, nor between vaccination and prevention of lower respiratory tract infections. Additionnal prospective studies are thus requested. In conclusion our study revealed that the vaccination coverage could be improved in patients with hematologic malignancies. Even if we failed to demonstrate the clinical usefullness of influenza vaccination, we believe that a better knowledge by physicians of studies demonstrating its tolerance and efficiency in this population could enhance the rate of vaccination.