When people think about influenza, they may picture a few uncomfortable days of fever, fatigue and time spent recovering at home. But for seniors 65 and older, influenza can pose a significant and cascading health risk.

As we age, our immune systems naturally weaken, making it harder to fight illnesses and increasing the risk of influenza infection.[1] The impact of an influenza infection can also extend far beyond the respiratory system. For the more than 80 per cent of seniors living with at least one chronic condition, such as diabetes, hypertension, or heart disease, a severe case of influenza can worsen existing conditions, interrupt daily routines and lead to serious long-term health complications.[2, 3]

Influenza has also been linked to a significantly increased risk of cardiovascular events, with research showing the risk of a heart attack may increase up to 10 times and the risk of stroke up to eight times following infection.[4]

“One of the lesser-known impacts of influenza is its potential impact on the cardiovascular system,” says Dr. Vivien Brown, CCFP, FCFP, MSCP, Assistant Professor, Department of Family & Community Medicine, University of Toronto. “Influenza can place significant stress on the body, particularly in older adults and those with underlying health conditions. It can act as a silent trigger for complications such as heart attack or stroke. Recovery may take weeks or months, and for some older adults, the setback can be life-altering.”

In Canada, the burden of influenza remains disproportionately high among seniors, with adults aged 65 and older accounting for 35 per cent of laboratory-confirmed influenza cases in 2025/2026.[5] In the previous influenza season, seniors accounted for nearly half of influenza-related hospitalizations across all age groups.[6]

Approximately one in five seniors experience a decline in their ability to carry out daily activities following influenza-related hospitalization.[7] This puts them at risk of losing their independence and tasks that were once routine, such as cooking, driving, or managing household responsibilities become more difficult.

“As someone who sees older adults in clinic, I’ve seen firsthand how quickly an influenza infection can take a serious turn,” says Dr. Brown. “In many patients, influenza triggers complications which can lead to hospitalization and have serious consequences for recovery and quality of life. That’s why protection against influenza is not just about avoiding illness. It’s about protecting your overall health, maintaining independence and being able to participate in everyday routines.”

Fortunately, there are preventative measures available that can help older adults lower their risk of influenza and its potentially serious consequences.

“Getting your influenza shot is the most effective way to prevent influenza and help reduce the severity of illness,” says Dr. Brown. “The high-dose vaccine helps protect seniors who are more vulnerable to influenza and its complications.” 

The National Advisory Committee on Immunization (NACI) preferentially recommends the high-dose influenza vaccine or other enhanced vaccines designed for seniors, when available.[8] The American College of Cardiology (ACC) also recommends the high-dose influenza vaccine as one of the options for adults 65 years and older, noting that it may help reduce the risk of hospitalization due to respiratory and heart-related complications compared to standard-dose influenza vaccines.[9] Research recently published in the Lancet has also shown that seniors who received a high-dose influenza vaccine were less likely to be hospitalized due to influenza, pneumonia and cardio-respiratory complications compared to those who received a standard-dose influenza vaccine.[10]

Fluzone High-Dose is a vaccine specifically designed to generate a stronger immune response in adults 65 years and older.[11] Containing four times the amount of antigens than standard-dose influenza vaccines, it has shown to be 24 per cent more efficacious in preventing influenza in seniors.[12, 13] 

Dr. Brown says in addition to vaccination, everyday precautions like hand washing, cleaning and disinfecting surfaces, or staying home when you’re sick, are all important ways seniors can help protect themselves and their families from influenza.[14]

Talk to your healthcare provider or pharmacist about one of the enhanced vaccines for seniors, such as Fluzone High-Dose and visit preventionhub.ca for more information about the vaccine, including potential side effects.*

As with any vaccine, Fluzone High-Dose may not fully protect all those who receive it.

*The most commonly reported side effects include pain at the injection site, muscle aches, headache and malaise. Consult the Product Monograph for complete safety information.

References

[1] Product Monograph. FLUZONE High-Dose. Sanofi Pasteur Limited. April 22, 2025.

[2] Canadian Institute for Health Information. Survey shows how health care experiences of older adults in Canada compare internationally. Available at: https://www.cihi.ca/en/survey-shows-how-health-care-experiences-of-older-adults-in-canada-compare-internationally

[3] Wang CS, Wang ST, Lai CT, Lin LJ, Chou P. Impact of influenza vaccination on major cause-specific mortality. Vaccine. 2007;25(7):1196-1203. doi:10.1016/j.vaccine.2006.10.015

[4] Warren-Gash C, Blackburn R, Whitaker H, McMenamin J, Hayward AC. Laboratory-confirmed respiratory infections as triggers for acute myocardial infarction and stroke: a self-controlled case series analysis of national linked datasets from Scotland. Eur Respir J. 2018;51(3):1701794. Published 2018 Mar 29. doi:10.1183/13993003.01794-2017

[5] Health Infobase. Canadian respiratory virus surveillance report: Influenza [page last updated May 1, 2026). Available at: https://health-infobase.canada.ca/respiratory-virus-surveillance/influenza.html [Last accessed: September 2026].

[6] FluWatch report: July 21 to August 24, 2024 (week 30-34). Government of Canada. Available at: https://www.canada.ca/en/public-health/services/publications/diseases-conditions/fluwatch/2023-2024/week-30-34-july-21-august-24-2024.html

[7] Andrew MK, MacDonald S, Godin J, et al. Persistent Functional Decline Following Hospitalization with Influenza or Acute Respiratory Illness. J Am Geriatr Soc. 2021;69(3):696-703. doi:10.1111/jgs.16950

[8] An Advisory Committee Statement (ACS) National Advisory Committee on Immunization (NACI). Statement on seasonal influenza vaccines for 2025–2026. Available at: https://www.canada.ca/en/public-health/services/publications/vaccines-immunization/national-advisory-committee-immunization-statement-seasonal-influenza-vaccines-2025-2026.html

[9] Heidenreich, P, Bhatt, A, Nazir, N. et al. Adult Immunizations as Part of Cardiovascular Care: 2026 ACC Concise Clinical Guidance: A Report of the American College of Cardiology Solution Set Oversight Committee. JACC. null2026, 0 (0).https://doi.org/10.1016/j.jacc.2026.07.004

[10] Johansen ND, Modin D, Pardo-Seco J, et al. Effectiveness of high-dose influenza vaccine against hospitalisations in older adults (FLUNITY-HD): an individual-level pooled analysis. Lancet. 2025;406(10518):2425-2434. doi:10.1016/S0140-6736(25)01742-8

[11] Product Monograph. FLUZONE High-Dose. Sanofi Pasteur Limited. April 22, 2025.

[12] Product Monograph. FLUZONE High-Dose. Sanofi Pasteur Limited. April 22, 2025.

[13] DiazGranados CA, Dunning AJ, Kimmel M, et al. Efficacy of high-dose versus standard-dose influenza vaccine in older adults. N Engl J Med. 2014;371(7):635-645. doi:10.1056/NEJMoa1315727

[14] Respiratory infectious diseases: Reduce your risk. Government of Canada. Available at: https://www.canada.ca/en/public-health/services/diseases/respiratory-infectious-diseases-reduce-spread-personal-protective-measures.html