Primary Care Fragmentation: Influenza vaccine inequity in universal care and buffering role of Community Health Centers

Background Canada provides publicly funded influenza vaccination for adults aged ≥65 years under universal healthcare, yet persistent coverage gaps remain. Existing research frequently conflates forms of primary-care fragmentation and rarely disentangles system-level and socioeconomic barriers to immunisation. This study examines vaccination inequities across primary-care continuity, inter-provider coordination, and socioeconomic dimensions among community-dwelling older Canadians. Methods Pooled 2015-2018 Canadian Community Health Survey data (n = 53,033 adults ≥65 years) were analysed. Multivariable logistic regression generated adjusted odds ratios (OR) and 99% confidence intervals (CI); interaction terms and income-stratified analyses were deployed to test effect modification. Exposures encompassed usual source of care, provider attachment, care coordination, household income, and educational attainment. Results Overall vaccination uptake reached 60.9%. Hierarchical gradients of primary-care fragmentation were detected; absence of a regular provider constituted the strongest structural barrier (OR=0.45, 99%CI 0.40-0.50). Income-stratified analyses identified a buffering effect of community health centres (CHCs), whereby CHCs partially offset vaccination deficits for low-income older adults facing moderate care fragmentation. Independent socioeconomic gradients and declining uptake with worsening inter-provider coordination were also observed. Conclusions Despite zero-cost influenza vaccination in Canada, primary-care fragmentation and socioeconomic disadvantage are independently associated with immunisation inequities. Results support gradient-tailored system-level interventions and targeted investment in CHCs to potentially mitigate disparities for marginalised older adults.