Effect of mobile phone text messaging for improving the uptake of influenza vaccination in patients with rare diseases.

Objectives: Influenza vaccine is recommended in some chronic medical conditions, including several rare diseases. The objectives of the study were to assess the effect of text message reminders on influenza vaccination uptake of patients with selected rare diseases and delayed vaccination, and to describe their characteristics.

Methods: Quasi-experimental pre-post intervention study performed along the 2016 influenza vaccination campaign in the Autonomous Community of Madrid. Unvaccinated patients diagnosed with a selected rare disease were targeted for intervention. SMS were sent to them at least one month after the beginning of the campaign, in four consecutive weeks. Those with no mobile phones available or no certainty of message reception, were assigned as controls. The association between the reception of the SMS and vaccination uptake was assessed using multiple poisson regression models.

Results: Of 69.040 patients with delayed vaccination, 87.2% received an SMS reminder in the asigned contact mobile telephone. Global influenza vaccine coverage reached 41.3%. The uptake of influenza vaccine was significantly higher among those receiving the reminder (9.3% vs. 7.1% in the control group, p < 0.001). Those who received a SMS reminder were 30% more likely to uptake seasonal influenza vaccine. By sex and age, the reception of the reminder was associated with a significantly higher probability of vaccination in men ≥65 years with at least a concurrent chronic condition (IRR: 1.58, CI95%: 1.25-2.00). Among women, this higher probability was detected in those between 14 and 64 years of age (IRR: 1.41, CI95%: 1.22-1.63), and ≥65 years without concurrent chronic conditions (IRR: 1.40, CI95%: 1.05-1.89).

Conclusion: Although the intervention was modestly effective, it proved beneficial in some cases. It can be an additional strategy to improve vaccine uptake, since it is simple, feasible, affordable and easily scalable, particularly when immunization and target population data are available in population registries.