Temporary Impact of the COVID-19 Pandemic on Influenza Vaccination Coverage
The results of this study indicate a notable decline in influenza vaccination coverage during the 2021–2022 season, the second year of the COVID-19 pandemic, followed by a rebound to pre-pandemic levels in subsequent seasons among all adults 18 years and older, and those aged 18–64 years without chronic medical conditions. The coverage remained stable among high-risk populations, including adults aged 18–64 with chronic medical conditions and those aged 65 and older, who are more vulnerable to influenza-related complications or hospitalization. However, vaccination coverage in these groups remained below the national target of 80%. Specifically, adults aged 18–64 with chronic medical conditions fell significantly short of this goal. While the coverage among seniors was closer to the target, it still did not reach the desired threshold.
Several factors likely contributed to the temporary drop in influenza vaccination coverage during the 2021–2022 season. During the first year of the COVID-19 pandemic, health authorities and infectious disease experts heightened public awareness and urgency around preventing any respiratory illness, including influenza, due to the uncertainty surrounding COVID-19 and the strain on healthcare facilities[15]. However, the pandemic disrupted routine healthcare services, making it more difficult for individuals to access vaccination throughout the pandemic years due to public health interventions[11, 16–18]. The 2021–2022 SIVCS on influenza vaccination coverage reported that 13.2% of the adult population were less likely to get the influenza vaccine due to the COVID-19 pandemic, with reasons including concerns about exposure to COVID-19 and disruptions in normal vaccination routines (e.g. lack of walk-in options)[19]. Additionally, the lockdowns and other measures may have reduced the perceived risk of contracting influenza, as both influenza and COVID-19 share similar transmission pathways. The focus on COVID-19 vaccination campaigns and mandatory policies likely overshadowed flu vaccination efforts, diverting attention and resources, and contributing to vaccine fatigue and decreased influenza vaccination rates [20–22]. The low influenza activity in the 2020–2021 season may have also reduced the perceived need for flu vaccination[23].
On the other hands, the rapid return and stabilization of influenza vaccination coverage to pre-pandemic levels indicate that the COVID-19 pandemic did not significantly increase awareness of the importance of other immunization, such as influenza vaccine. Vaccine hesitancy related to concerns about COVID-19 vaccines may have influenced attitudes towards other vaccines, including the influenza vaccine[11, 18, 24]. A recent article noted that misinformation and safety concerns about COVID-19 vaccines can spill over into general vaccine skepticism, affecting uptake of other vaccines[25]. However, some studies have shown that the pandemic led to increased intent to vaccinate against influenza, suggesting that the pandemic could be a window of opportunity to promote influenza vaccination and decrease vaccine hesitancy[11, 26, 27]. This is an area that needs further investigation to understand the differences between these reactions and how best to encourage vaccine acceptance.
For high-risk groups, such as adults with chronic medical conditions and older adults, the consistency in influenza vaccination coverage over time is likely due to the higher perceived risk of severe influenza outcomes and the prioritization of these groups by healthcare providers. However, the low uptake among younger adults with chronic medical conditions is particularly concerning given their vulnerability to severe influenza outcomes. Ensuring targeted interventions for this subgroup is crucial to improving their vaccination rates.
Despite the challenges faced during the 2021–2022 season, the return to pre-pandemic influenza vaccination levels in the 2022–2023 and 2023–2024 seasons is encouraging, although an increase in coverage might have been expected due to heightened awareness. This rebound suggests that the decline in influenza vaccine uptake was temporary and short-term, unlike the more enduring impact of the pandemic on routine childhood vaccination programs, which continue to experience declining coverage [28]. The temporary drop in influenza vaccine uptake may be associated with increased hesitancy among younger populations, influenced by pandemic-related factors. In contrast, the long-term decline in routine childhood vaccinations may due to more persistent disruptions, such as reduced access to healthcare, school closures, and shifts in healthcare priorities, which have had a cumulative effect on vaccination rates. Several factors likely contributed to the quick recovery in influenza vaccination coverage, including the co-administration of influenza and COVID-19 vaccines. The co-administration of influenza and COVID-19 vaccines provided convenient access, with 71.3% of people receiving both vaccines simultaneously according to the 2023–2024 SIVCS. The overlap between the flu season and ongoing COVID-19 concerns could have prompted people to seek out additional protection against respiratory illnesses, especially given the co-administration opportunities. Expanded access through pharmacies and mass vaccination clinics originally set up for COVID-19 vaccinations also facilitated broader influenza vaccine uptake. Furthermore, British Columbia expanded its influenza vaccination program in the fall of 2021, followed by Quebec in the fall of 2022, making the influenza vaccine free for all individuals aged 6 months and older[29, 30]. These changes aligned with other Canadian jurisdictions' policies and likely contributed to increased vaccination uptake in these regions. These efforts, combined with public health campaigns highlighting the importance of both influenza and COVID-19 vaccines, helped restore public trust in vaccination, effectively mitigating pandemic-related disruptions and addressing vaccine fatigue[31, 32]. Subsequently, influenza vaccination coverage rebounded swiftly.
Changes in Vaccination Locations
The data also shows a shift in the places where influenza vaccines were administered. Notably, there was a substantial increase in vaccinations at pharmacies, which rose from 35.4% in 2018–2019 to 57.4% in 2023–2024. This increase can be linked to the expanded role of pharmacies in Canada, where they have been authorized to administer influenza vaccines in community pharmacies[13, 33, 34]. Studies have demonstrated that influenza vaccine uptake has modestly increased in Canadian jurisdictions where pharmacists were allowed to administer influenza vaccines given their ubiquitous distribution, extended working hours, walk-in policies and availability to people without a primary care provider [33, 34].
Permanent or temporary vaccine clinics, such as those set up in malls, also saw increased utilization, peaking at 12.1% in 2022–2024. The increase was likely due to the mass COVID-19 vaccination campaign. These clinics offered convenient and accessible options for people to get vaccinated against COVID-19, influenza and other vaccines outside of traditional healthcare settings, which was particularly important during the pandemic to improve vaccine accessibility[35].
Conversely, vaccinations in doctor's offices and health clinics declined significantly from 32.7% in 2018–2019 to 15.2% in 2023–2024. This reduction was associated increased availability and convenience of alternative vaccination sites such as pharmacies and temporary clinics, as well as reduced in-person healthcare visits during the pandemic[11].
Overall, the shift in vaccination settings reflects a broader trend towards making vaccinations more accessible and convenient, which is crucial for maintaining high vaccination coverage, especially during public health emergencies like the COVID-19 pandemic.
Strengths and Limitations
One of the primary strengths of this study is the consistency in survey design and target population, allowing for reliable coverage and data comparison over time. The use of a stratified regional sampling approach ensures representation across all provinces and territories of Canada, making the results reflective of the entire Canadian adult population. This comprehensive sampling methodology enhances the generalizability of the findings and provides valuable insights into vaccination behaviors and trends across different demographics.
Despite the strengths of this study, several limitations must be acknowledged. First, as with any survey-based research, there is potential for response bias. Participants might overreport or underreport their vaccination status, influenced by social desirability or recall bias. Second, the exclusion of individuals without access to landlines or cellphones, although minor, could slightly bias the results, particularly among populations with lower socioeconomic status and those living in retirement residences or eldercare centers who might be underrepresented in the sample. Additionally, the response rates ranged from 10–20%, which is typical for telephone surveys, the reliance on quota sampling—where households unwilling to participate are replaced until quotas are met—limits the ability to accurately quantify the probability of selection. This non-probabilistic approach, coupled with the low response rates, reduces the representativeness of the sample and introduces potential nonresponse bias, as differences between respondents and non-respondents are not fully addressed.