• Last updated: Wed, Apr 26, 2023Status: Ongoing
• Tove Fall, Georgios Varotsis, Carl Bonander, Anna Sarkadi, Helena Svaleryd, and Ulf Hammar

Pre-Booked Appointment Letters for Increasing Vaccination Coverage in Target Populations

Prevention is a key task for the healthcare system, as is provision of equitable healthcare for the whole population. Vulnerable groups for adverse outcomes of respiratory infections include the elderly, groups with low socioeconomic status (SES), and those living with certain chronic diseases, groups that traditionally have lower vaccination uptake rates. There is therefore a need to find tools that increase vaccination coverage among these groups. In Sweden, regional strategies have included vaccination buses and drop-in vaccinations. Nonetheless, these approaches may exclude individuals with lower literacy levels and rely on self-initiated appointments. In Uppsala County individual pre-scheduled appointment notifications for both dose 1 and dose 2 of the COVID-19 vaccine were sent by post to everyone ≥50 years and those aged 17-18. Those aged 18-49 years were informed only by SMS when they were eligible to self-book an appointment.

Pre-booked appointment letters can personalize vaccination strategies and eliminate barriers in the vaccination process, particularly among vulnerable groups. This study aims to evaluate the role of pre-booked appointment letters on vaccination uptake and severe COVID-19 outcomes during 2021/2022. We will perform a regression discontinuity analysis to estimate the effect of the individual appointment as a discontinuous function of age at the age cut-off. We will also assess the number of additional vaccinations occurring as a result of the individual appointment notifications 1) in low-SES groups and 2) in patients at higher risk for severe COVID-19. We will attempt to estimate the effect on hospitalizations. Finally, we will also use a sibling design to compare sib-pairs with one sibling in Uppsala and the other outside Uppsala in the target groups. We will also assess household spill-over effects.

In summary, this project applies causal inference analysis using natural experiment techniques successfully used in econometrics. Our evaluation seeks to address barriers to vaccination and improve future vaccination campaigns in Sweden.