Endocrine Abstracts

JOINT1347

Background: 20% of all confirmed influenza cases are admitted to hospitals in Denmark. Underlying conditions such as type 1 diabetes (T1D) can lead to increased risk of severe complications from influenza. In Denmark, influenza vaccination is recommended to all adults with T1D, and the World Health Organization (WHO) recommends an influenza vaccination coverage (IVC) of 75% in high-risk groups. This register-based, repeated cross-sectional study aims to investigate IVC among individuals with T1D and identify subgroups susceptible to non-vaccination.

Methods: Using nationwide Danish registers, we compiled a cohort of adults in Denmark aged 19-64 with T1D during influenza seasons 2015/16-2022/23. Vaccination status was assessed prior to every influenza vaccination season. We investigated associations between non-vaccination and gender, region of residence, age at T1D onset, T1D duration, hemoglobin A1c, socioeconomic status and events of severe hypoglycemia and/or ketoacidosis using robust Poisson regression to compute adjusted relative risk (RR).

Results: IVC was low in the 2015/16 season (IVC 17. 99%, 95% confidence interval (CI) (17. 44%, 18. 54%)), and increased slightly throughout seasons 2016/17-2020/21. In 2021/22, IVC increased significantly to 41. 13% (95% CI (40. 45%, 42. 18%)). Male sex was associated with not receiving influenza vaccination (RR 0. 75, 95% CI (0. 73, 0. 77)). Age at onset and T1D duration was also associated with vaccination status: As these increase, so does the likelihood of vaccination. Individuals with HbA1c > 53 mmol/mol had a reduced RR of vaccination (RR 0. 97, 95% CI (0. 95, 0. 99)). Region of residence and socioeconomic factors were strongly associated to RR of vaccination. Diabetic ketoacidosis prior to season start showed a significant decrease in RR of vaccination by 12% (RR 0. 88, 95% CI (0. 83, 0. 92)).

Conclusions: This study reveals that IVC among individuals with T1D is suboptimal and does not meet the recommendations set by the WHO. Although IVC seems to be increasing, more intense and tailored vaccination strategies are needed to increase it further. We have identified several factors that are associated with non-vaccination, revealing specific subgroups that healthcare providers should prioritize in vaccination efforts.