Uptake rates of influenza vaccination in over 65s in Denmark: a comparison between Danish-born and migrant populations, 2015-21.

WHO's Immunization Agenda 2030 has placed renewed focus on life-course vaccination, including among migrants. Despite the availability of a seasonal vaccine, influenza remains a key contributor to winter excess mortality in Northern Europe, yet limited data on influenza vaccination uptake in migrants has been published. We analyzed Danish national registry data to determine influenza vaccine uptake across six flu seasons (2015/16-2020/21) among migrants (asylum-pathway and quota refugees, family reunified migrants) ≥65 years matched 1:6 on age and gender to Danish-born individuals. We used multivariate logistic regression models controlling for migrant status (immigration status, time in Denmark) and other sociodemographic variables (age, gender, nationality, urban/rural residence) to identify factors associated with influenza vaccination uptake. All analyses were done in R v4.2.1. Across all six seasons, overall flu vaccination uptake was 49.3% (Danish-born: 50.9%; migrant cohort: 39.4%). Migrants were less likely [odds ratio (OR): 0.66; 95% confidence interval (CI): 0.64-0.67] to receive an influenza vaccine across all seasons, with this gap widening from 2015/16 (OR: 0.78; 95% CI: 0.74-0.84) to the 2020/21 season (OR: 0.44; 95% CI: 0.42-0.46). Family-reunified migrants were less likely to receive an influenza vaccine across the study period than asylum-pathway and quota refugees and those from the Sub-Saharan Africa region had the lowest uptake in terms of area of origin. This large and unique dataset shows that migrant groups have lower uptake rates for influenza vaccination compared with Danish-born individuals, with the gap widening over time. Going forward, developing tailored interventions, co-developed in collaboration with communities themselves, will be key.