Influenza vaccination in cancer patients undergoing systemic therapy

Background: Cancer patients often experience preventable infections, including influenza A and B. These infections can be a cause of significant morbidity and mortality. The increased risk of infection may be because of either cancer itself or treatment-induced immunosuppression.¹ Influenza immunization has been shown to decrease the risk of influenza infection in patients with intact immunity.² In cancer patients, active immunization has been shown to confer protective immunity against several infections at similar rates to healthy individuals, which has translated into decreased duration and severity of infection and potentially improved morbidity and mortality.³ Objectives: 1. To assess the efficacy of influenza vaccination in stimulating immunological response in patients with cancer during chemotherapy compared to control groups. 2. To assess the efficacy of influenza vaccination in preventing confirmed influenza and influenza-like illness and/or stimulating immunological response in children with cancer treated with chemotherapy, compared to placebo, no intervention, or different dosage schedules. 3. To determine the adverse effects associated with influenza vaccination in patients with cancer. Search methods: We searched MEDLINE/PubMed database for articles published from 1964 to 2013 using the search terms "cancer, " "adult, " "influenza vaccination, " and "chemotherapy." Selection criteria: We included studies based on systematic sampling with defined clinical criteria irrespective of the vaccination status of cancer patients. Studies measure the serological response or clinical response to compare between the study group and the control group. Studies assessed the inactivated influenza vaccines and live attenuated influenza vaccine (LAIV) protective serological reaction and the clinical outcomes after vaccination. Data collection and analysis: Two independent authors assessed the methodological quality of included studies and extracted data. Main results: We included 16 studies (total number of participants = 1, 076). None of the included studies reported clinical outcomes. All included studies reported on influenza immunity and adverse reaction on vaccination. We included 6 solid tumor studies and 10 hematological studies. In 12 studies, the serological response to influenza vaccine was compared in patients receiving chemotherapy (n = 425) versus those not receiving chemotherapy (n = 376). In three studies, the serological responses to influenza vaccination in patients receiving chemotherapy are compared to that in healthy adult. Measures used to assess the serological responses included a four-fold rise increase in antibody titer development of hemagglutination inhibition (HI) titer.40, and pre- and post-vaccination geometric mean titers (GMTs). Immune responses in patients receiving chemotherapy were consistently weaker (four-fold rise of 17-52%) than in those who had completed chemotherapy (50-83%) and healthy patients (67-100%). Concerning adverse effects, oncology patients received influenza vaccine, and the side effects described were mild local reactions and low-grade fever. No life-threatening or persistent adverse effects were reported. Authors' conclusion: Patients with solid and some of hematological tumors are able to mount a serological response to influenza vaccine, but it remains unclear how much this response protects them from influenza infection or its complications. Meanwhile, influenza vaccine appears to be safe in these patients. While waiting results of randomized controlled trials to give us more details about the clinical benefits of the influenza vaccination, the clinicians should consider the currently proved benefits of influenza vaccination on management of the cancer patients undergoing systematic chemotherapy such as decrease in the duration and severity of the of the disease, and significant decrease in influenza-associated morbidity and mortality in these high-risk patients.³