Influenza vaccine effectiveness among cancer patients: A population-based study using health administrative and laboratory testing data from Ontario, Canada

Surveillance of the current situation regarding influenza vaccination according to medical oncologists in Japan

“…Some studies have reported that the efficacy of influenza vaccination in particular subsets of cancer patients, such as those with lung cancer 28 or breast cancer, 22,29 is equivalent to that in healthy people. In contrast, other studies have shown that the response to influenza vaccination is poor in patients with a hematologic malignancy such as multiple myeloma (MM) or non‐Hodgkin lymphoma 12,25,26,30 . The present work found that approximately 20% of medical oncologists do not recommend influenza vaccination to patients with a hematologic malignancy, specifically malignant lymphoma (ML), acute leukemia, or MM.…”

“…Furthermore, conducting an RCT might be unethical if patients in the control arm were not given any vaccine. To overcome these issues, the design employed by Blanchette et al, in which vaccination history was linked to large‐scale hospital administrative data, could be useful 12 . In Japan, insurance claim data, which has long been used for payment, has recently become available for research.…”

“…A systematic review that included this study by Earle et al reported a significant reduction in mortality among the influenza vaccine group, although the number of observations was small, and the evidence level was assessed as being weak 19 . Based on a relatively large‐scale population‐based study employing a test negative design, Blanchette et al reported that the effectiveness of influenza vaccination in cancer patients was approximately 20%; however, details on the concurrent medications, chemotherapy regimens, and vaccination timing were not specified 12 . Therefore, although the available data suggest that influenza vaccination among cancer patients undergoing chemotherapy may have some positive effect, the evidence on its effectiveness is still insufficient.…”

“…Regarding cancer patients, 1 study conducted among patients with colorectal cancer, which is one of the most prevalent types of cancer in Japan, reported that influenza vaccination significantly decreased pneumonia development, all‐cause mortality, and chemotherapy discontinuation 11 . However, the effectiveness of influenza vaccination for individuals with cancer is somewhat unclear when compared with its effectiveness for immunocompetent people because of the small sample sizes and methodological limitations of the studies conducted on this population 3,9,12 . Research performed outside Japan found low rates of influenza vaccination among those with cancer, stemming from uncertainty about its effectiveness, fear of side effects, and a lack of data regarding the appropriate timing for vaccine administration 13,14 .…”

“…11 However, the effectiveness of influenza vaccination for individuals with cancer is somewhat unclear when compared with its effectiveness for immunocompetent people because of the small sample sizes and methodological limitations of the studies conducted on this population. 3,9,12 Research performed outside Japan found low rates of influenza vaccination among those with cancer, stemming from uncertainty about its effectiveness, fear of side effects, and a lack of data regarding the appropriate timing for vaccine administration. 13,14 Because patients in Japan tend to be dependent and passive, and they have few opportunities to participate in medical decision-making, 15 the physician's attitude toward influenza vaccination is very likely to influence their patient's behavior.…”