Uptake of flu vaccination in Denmark: A comparison between Danish and migrant populations, 2015-2021

WHO's Immunisation Agenda 2030 emphasises vaccination across the life course, including among migrants who may be at-risk in terms of access and uptake. Despite availability of a vaccine, influenza remains a key contributor to winter excess mortality in Europe. We analysed national Danish Registry Data to determine how flu vaccine uptake varies by migration status. We carried out a retrospective cohort study (2015-2020) to determine flu vaccine uptake among migrants ≥65 years matched 1:6 on age and gender to Danish-born. We used a multivariate logistic regression model (in R v4.2.1), controlling for migrant status, time in Denmark and other socio-demographic variables (age, gender, nationality, urban/rural residence), to identify factors associated with uptake. 81,644 individuals were included in the analyses. The flu vaccine uptake across 6 flu seasons in Danish-born was 44.7%, compared with 34.7% in the migrants. Migrants were statistically significantly (OR:0.64; 95% CI:0.62-0.65) less likely to receive a flu vaccine across all seasons; the gap widened from 2015 (OR:0.76; 95% CI:0.72-0.80) to 2020 (OR:0.49; 95% CI:0.47-0.51). Those who arrived as family-reunified to Danish citizens (OR:0.51, 95% CI:0.45-0.58) or to immigrants (OR: 0.58, 95% CI:0.47-0.71) were statistically significantly less likely to receive the vaccine across the study period than asylum seekers and refugees. In 2015-2017 seasons, those residing in Denmark >10 years were more likely (2015 OR:2.06, 95% CI:1.56-2.73; 2016 OR:2.35, 95% CI:1.75-3.15); 2017 OR:1.92, 95% CI:1.41-2.61) to receive a vaccine than those more recently arrived. Our data show that flu vaccine uptake was poor in all groups but that migrant groups have consistently lower uptake rates, particularly among family-reunified migrants and those more recently arrived. Migrant flu vaccination rates in migrants fell over a 6-year period. Going forward, developing tailored interventions in collaboration with communities will be key. KEY MESSAGES: • Migrant groups have consistently lower uptake rates of flu vaccination than Danish born. • Newly arrived migrants are significantly less likely to get vaccinated, suggested targeted interventions may be needed.