The safety of seasonal influenza vaccination among adults prescribed immune checkpoint inhibitors: A self-controlled case series study using administrative data.

Feb 12, 2024

Immune checkpoint inhibitor (ICI) therapy for patients undergoing cancer treatment carries a risk of severe immune-related adverse events (IRAEs). Questions remain about whether seasonal influenza vaccination might increase the risk of developing IRAEs among these patients given that vaccines are immunomodulatory. Previous vaccine safety studies on patients with cancer prescribed ICI therapy have demonstrated conflicting results.
Using health administrative data from Ontario, Canada among adults diagnosed with cancer who had been prescribed ICI therapy and who had received an influenza vaccine from 2012 to 2019, we conducted a self-controlled case series study. The pre-vaccination control period started 42-days post-ICI initiation until 14-days prior to vaccination, the risk period was 1-42 days post-vaccination, and the post-vaccination control period was after the risk period until ICI discontinuation or a maximum period of two years. Emergency department (ED) visit(s) and/or hospitalization for any cause after ICI initiation was used to identify severe IRAEs. We fitted a fixed-effects Poisson regression model accounting for seasonality and calendar time to estimate relative incidence of IRAEs between risk and control periods.
We identified 1133 records of cancer patients who received influenza vaccination while prescribed ICI therapy. Most were aged ≥ 66 years (73 %), were male (63 %), had lung cancer (54 %), and had received ICI therapy with a programmed cell death protein 1(PD-1) inhibitor (91 %). A quarter (26 %) experienced an ED visit and/or hospitalization during the observation period. Rates of ED visits and/or hospitalizations in the risk vs. control periods were similar, with an incidence rate ratio of 1.04 (95 % CI: 0.75-1.45). Subgroup and sensitivity analyses yielded similar results.
Seasonal influenza vaccination was not associated with an increased incidence of ED visit or hospitalization among adults with cancer treated with ICI therapy and our results support further evidence of vaccine safety.

Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.

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ABOUT THE EXPERTS

Alicia A Grima, Jeffrey C Kwong, Lucie Richard, Jennifer Reid, Jacques Raphael, Nicole E Basta, Alex Carignan, Karina A Top, Nicholas Brousseau, Phillip S Blanchette, Maria E Sundaram,
Alicia A Grima

Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada.

Jeffrey C Kwong

Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada; ICES, ON, Canada; Public Health Ontario, Toronto, ON, Canada; Centre for Vaccine Preventable Diseases, University of Toronto, Toronto, ON, Canada; Department of Family and Community Medicine, University of Toronto, Toronto, ON, Canada; University Health Network, Toronto, ON, Canada.

Lucie Richard

ICES, ON, Canada.

Jennifer Reid

ICES, ON, Canada.

Jacques Raphael

ICES, ON, Canada; Division of Medical Oncology, Department of Oncology, London Regional Cancer Program, London Health Sciences Centre, Western University, London, ON, Canada.

Nicole E Basta

Department of Epidemiology, Biostatistics and Occupational Health, School of Population and Global Health, McGill University, Montreal, QC, Canada.

Alex Carignan

Department of Microbiology and Infectious Diseases, Université de Sherbrooke, Sherbrooke, QC, Canada.

Karina A Top

Departments of Pediatrics and Community Health & Epidemiology, Dalhousie University, Halifax, NS, Canada.

Nicholas Brousseau

Institut national de santé publique du Québec, Quebec City, QC, Canada; Département de Médecine Sociale et Préventive, Université Laval, Quebec City, QC, Canada.

Phillip S Blanchette

ICES, ON, Canada; Division of Medical Oncology, Department of Oncology, London Regional Cancer Program, London Health Sciences Centre, Western University, London, ON, Canada. Electronic address: phillip.blanchette@lhsc.on.ca.

Maria E Sundaram

ICES, ON, Canada; Center for Clinical Epidemiology and Population Health, Marshfield Clinic Research Institute, Marshfield, WI, USA. Electronic address: sundaram.maria@marshfieldresearch.org.