PREPARED BY: Immunization

DATE: 2026-06-25

Influenza (flu) is a substantial cause of seasonal respiratory illness and can result in severe outcomes, particularly among infants, young children, older adults, pregnant individuals, and individuals with underlying medical conditions. Annual influenza vaccination remains a key public health measure to lower the risk of severe illness and hospitalization and ease pressure on the healthcare system during the respiratory illness season.

Ontario’s publicly funded universal influenza immunization program (UIIP) provides access to influenza vaccine through primary care providers, pharmacies, hospitals, long-term care homes, retirement homes, and other community-based settings. The Windsor-Essex County Health Unit (WECHU) plays a key role in supporting the local UIIP in Windsor and Essex County (WEC) through vaccine inventory management and distribution, provider communication and support, direct immunization opportunities, and ongoing review of local surveillance and epidemiological data. The WECHU also oversees timely investigation and reporting of adverse events following immunization (AEFI).

DISCUSSION

Data from Public Health Ontario’s Respiratory Virus Tool shows that influenza virus circulated throughout the 2025–2026 respiratory illness season in WEC, with activity increasing early in the season and peaking in December 2025. From September 1, 2025, to the week beginning May 3, 2026, the average weekly combined influenza percent positivity in WEC was 10.3%, peaking at 40.6% in the week beginning December 21, 2025. Influenza A was the primary driver of local influenza activity during the season, peaking at 40.3% positivity in the week beginning December 21, 2025. Influenza B activity increased later in the season, peaking at 10.8% positivity in the week beginning March 8, 2026. During the 2025–2026 respiratory illness season, WEC recorded 1,279 reported influenza cases, representing a rate of 255.4 cases per 100,000 population. This was comparable to the provincial reported influenza case rate of 235.0 cases per 100,000 population during the same period. Weekly local case counts peaked at 210 cases in the week beginning December 21, 2025. Cases were reported across all age groups, with the highest counts among children aged 1 to 4 years, adults aged 60 to 79 years, children aged 5 to 11 years, and adults aged 80 years and older. During the same period, WEC recorded 249 influenza hospital admissions, representing a rate of 49.7 admissions per 100,000 population. This was comparable to the provincial influenza hospital admission rate of 51.8 admissions per 100,000 population. Weekly local admissions peaked at 58 hospital admissions in the week beginning December 28, 2025.

Influenza Vaccine Distribution

In Ontario, local supply of influenza vaccine is received by public health units from the Ontario Government Pharmacy in predetermined quantities dependent on provincial vaccine availability. Allocation to local providers is based on factors such as doses available, number of clients to be served, past administration, available approved storage, proportion of high-risk clients the provider is connected to, etc.

During the 2025–2026 respiratory illness season, the WECHU distributed 83,610 influenza vaccine doses to WEC providers, compared to 79,140 doses in 2024-2025. Vaccine was distributed to providers practicing across all municipalities reflecting broad provider participation and strong regional distribution to support access for eligible populations. 

*This total does not include doses distributed to WEC pharmacies. Pharmacy providers receive their vaccine supply directly from provincial distributors.  

Influenza Immunization Activity

Although local administration percentages by provider/setting are not available for all WEC providers, provincial Ministry of Health UIIP data for the 2025–2026 season, as of December 31, 2025, show that influenza vaccine administration occurred primarily through pharmacies and physicians. Provincially, pharmacies administered 69% of influenza vaccine doses and physicians administered 29% of doses, while public health units administered 1% and all other settings accounted for less than 1%. This provincial pattern provides context for WECHU’s role within the broader influenza vaccine delivery model. Pharmacies and physicians provide the majority of influenza immunizations to clients, while public health units play a complementary role through vaccine distribution, provider support, surveillance, public communication, and targeted direct immunization opportunities. During the 2025–2026 season, the WECHU directly administered 214 influenza vaccine doses, compared to 517 in the 2024–2025 season. Vaccination opportunities were provided through in-office clinics and mobile community clinics, with a focus on reducing barriers for individuals at higher risk of severe outcomes and priority populations experiencing access barriers. Influenza vaccines were co-administered with COVID-19 and/or RSV vaccine when clients were eligible.

Local vaccine confidence research also highlights the importance of continued public education and trust-building as part of influenza immunization efforts. Ipsos research conducted for the WECHU in 2025 found that over one-third of WEC residents reported hesitancy towards flu vaccine and other seasonal vaccines such as COVID-19, and self-reported flu vaccine uptake was lower among vaccine-hesitant respondents compared to vaccine-confident respondents. These findings suggest that influenza vaccine uptake is influenced not only by access, but also by attitudes, trust, and confidence in vaccination.

Program Planning for 2026–2027

For the 2026–2027 respiratory illness season, the WECHU will continue to adapt its local influenza immunization approach, informed by Ministry direction, local surveillance trends, provider feedback, community needs, and vaccine confidence data. Program planning will also place greater emphasis on innovative public messaging that positions influenza immunization as part of broader chronic disease prevention by helping reduce severe illness, hospitalizations, and complications that can worsen or contribute to outcomes such as myocardial infarction, stroke, and functional decline among older adults, including those at risk of dementia. Priority areas for continued improvement include:

• Leveraging local health and vaccine metrics to strengthen targeted communications and interventions.
• Enhancing early collaboration and planning with primary care providers, pharmacies, hospitals, long-term care homes, retirement homes, and other community partners.
• Implementing an innovative, targeted, multi-pronged communication strategy that promotes annual influenza vaccination using timely reminders, plain-language digital and community-based messaging, and evidence-informed framing that highlights the role of vaccination in chronic disease prevention, including reducing the risk of severe outcomes that may contribute to myocardial infarction, stroke, and health decline among older adults and other high-risk populations.
• Strengthening vaccine confidence messaging by using clear, plain-language information that addresses common concerns related to vaccine safety, effectiveness, and trust. 
• Continuing to provide direct immunization opportunities for high-risk populations, including in-office seasonal clinics and mobile community clinics.