Multiple mail reminders to increase adherence to influenza vaccination.

Different interventions have been proposed to reinforce the use of the influenza vaccine. The use of reminders, whether through letters, phone calls, pamphlets or technological applications, among others, has stood out among those aimed at increasing ad-herence to treatment. However, its effectiveness is not clear. In this summary, which is part of a series of reminder evaluations, we assess the use of multiple mail reminders.
We conducted a search in Epistemonikos, the largest database of systematic health reviews, which is maintained by screening multiple sources of information, including MEDLINE, EMBASE, Cochrane, among others. We extracted the data from the identified reviews, analyzed the data from the primary studies, performed a meta-analysis and prepared a summary table of the results using the GRADE method.
We identified eight systematic reviews including 35 primary studies, of which four analyze the use of more than one letter as a reminder. We conclude that the use of multiple mail reminders probably increase adherence to influenza vaccination in patients over 60; while it may make little or no difference in children under 6 years, but the certainty of the evidence is low.