Efficacy and Safety of Influenza Vaccination During Chemotherapy Treatment

We have read with interest the paper recently published in the Journal of Supportive Oncology about the lack of compliance with national vaccination guidelines in patients receiving radiation therapy.¹ Cancer patients, in particular those receiving chemotherapy and/or radiotherapy, are at an increased risk of contracting influenza and may have higher complication and mortality rates than the general immunocompetent population.^{[2] and [3]}

Patient safety goals recently issued by the Joint Commission on the Accreditation of Healthcare Organizations (JCAHO) and current Centers for Disease Control and Prevention (CDC) guidelines recommend vaccinations for all cancer patients over the ages of 65 (for pneumococcus) and 50 (annually, for influenza).^{[4] and [5]} Moreover, in a recent review, Pollyea et al.² reported that vaccination against seasonal influenza is indicated in immunocompromised patients, including those receiving anticancer chemotherapy, irrespective of their age.

However, there is some uncertainty among oncologists about the safety and efficacy of this procedure. Evidence indicates that fewer than 50% of patients treated with chemotherapy actually receive a vaccination.⁶ As published by Yee et al.,¹ 30% of patients treated with radiotherapy reported never receiving the influenza vaccine and only 7% of patients reported being asked or informed about the vaccination by their oncologists.

This uncertainty is probably due to several limitations in the available studies on this subject.² Considering these limitations, we carried out an observational monocentric study to evaluate influenza vaccine efficacy and safety in patients undergoing chemotherapy.

We included patients who received an influenza vaccination in November 2008 during chemotherapy treatment. In January–February 2009, we collected the patients' clinical information about cancer disease (type and stage), chemotherapy treatment (adjuvant or palliative treatment, line of therapy), comorbidities, concomitant medications, and previous seasonal influenza vaccination. In March 2009, eligible patients were interviewed to determine if they had contracted influenza (according to the WHO definition: sudden onset of fever >38°, with at least one general symptom such as aching muscles, headache, and malaise and at least one respiratory symptom such as nonproductive cough, sore throat, and rhinitis) and developed a vaccination reaction.

Seventy-two patients, including 38 (52%) females with a median age of 69 years, received vaccination during chemotherapy. Thirty (42%) patients were treated with adjuvant chemotherapy and 42 (58%) for locally advanced or metastatic disease. Twenty-five (35%) patients were treated for gastrointestinal, 17 (24%) for breast, 14 (19%) for urogenital, and 11 (15%) for lung cancers, as well as four for other solid tumors. Eighteen (25%) patients received vaccination for the first time. We found seven (9%) cases of influenza and only three (4%) vaccination reactions (transient muscle soreness, arthralgias, and fever). Considering our results in terms of efficacy and safety, routine vaccination against influenza virus should be considered in patients undergoing chemotherapy.

Our observations have several limitations, represented, in particular, by the absence of a control, nonvaccinated group and of a “true” measure of efficacy vaccination (such as serological response). Nevertheless, the limited sample size, the heterogeneity of the available studies, and the absence of a randomized controlled trial make even an observational study, such as that reported by our institution, valuable.