‘Reassuring’ Findings Show That Flu Shot Is Safe During Immunotherapy

The seasonal influenza (flu) vaccine appears to be safe in patients with cancer who are undergoing immune checkpoint inhibitor treatment, according to recent research that was presented at the 2023 American Society of Clinical Oncology Annual Meeting.

Immune checkpoint inhibitors are a type of immunotherapy that helps the immune system find and fight the cancer. Since these drugs alter the immune system, there was concern that administering the flu vaccine to patients taking them would exacerbate the risk of dangerous immune-related side effects and safety issues.

However, that proved not to be the case.

“We did not identify any increased risk associated with influenza vaccine,” study author, Dr. Phillip Blanchette, from the London Health Services Center, said while presenting the findings.

Blanchette and his team analyzed data of 1,233 patients who were receiving immune checkpoint inhibitor treatment and were administered the flu vaccine betweenDec. 31, 2019 and Jan. 1, 2023. Nearly two-thirds (73%) of patients were aged 66 or older, and 63% were male. Patients with the following cancer types were included in the study:

• Lung cancer (54% of participants)
• Malignant melanoma (31%)
• Kidney cancer (8%)
• Bladder cancer (5%)
• Head and neck cancers (2%)

The average time from the start of immune checkpoint inhibitor treatment to the seasonal flu vaccine was 184 days, with the majority of patients receiving the vaccine between 98 and 325 days of starting immunotherapy.

The main goal of the trial was to see if there was an increase in emergency department visits and/or hospitalizations after patients had the vaccine. The researchers also looked at the use of corticosteroid or immunosuppressive treatment (which is commonly used to treat immune-related side effects from immunotherapy) and the frequency of severe side effects pre- and post-vaccine.

Study findings showed similar instances of emergency department/hospitalizations between the pre-and post-vaccine periods, indicating that the flu vaccine did not cause an increase. Similarly, there were no major differences seen in corticosteroid/immunosuppression use or visits to a specialist for severe side effects.

These findings are particularly important because there has been an increase in influenza cases after the COVID-19 pandemic, according to research from the International Journal of Infectious Diseases. Additionally, according to the National Foundation for Cancer Research, patients with cancer are not at an increased risk for catching the flu, but they may be at risk of complications from infection, such as dehydration, bronchitis or pneumonia, worsened lung or heart conditions and death.

That said, the Centers for Disease Control and Prevention (CDC) recommends that everyone ages six months and older get a flu vaccine every season.

“Flu vaccination is especially important for people with cancer or a history of cancer, because they are at a higher risk of developing serious flu complications,” the CDC said in a statement. “It is also important for people who with or care for cancer patients to be vaccinated against seasonal flu to reduce the risk of getting the cancer patient sick.”

Now, the research by Blanchette and colleagues supports that recommendation.

“In all these analyses, the event rate both during the risk and control periods were similar, and we did not identify any increased risk associated with influenza vaccination,” Blanchette explained. “Our study results should be reassuring to patients and clinicians regarding the safety of the influenza vaccination. Our results support current clinical guideline recommendations to continue to offer influenza vaccination to cancer patients receiving immune checkpoint inhibitor therapy.”

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