A systematic review of email-based reminder interventions to increase vaccine uptake

Abstract

Introduction Reminder and recall interventions have been proven to be effective in increasing vaccination coverage. Emails are a popular method of communication, but their use for health communication is still sporadic. The use of email as a reminder method has many potential benefits: the cost is low, the delivery is timely and there is no restriction of content. Nevertheless, there is limited evidence on the advantages of using emails for reminders with respect to other methods, on which extensive literature is already present, to increase the uptake of vaccination. In this review we collected all available evidence on this tool, in order to prioritize future actions. Methods We conducted a systematic review following the PRISMA guidelines to analyze the available evidence from peer-reviewed studies on the effect of email-based interventions applied to immunization programs. We included any measure of vaccine uptake or immunization coverage, in any target population and settings. Results We included 11 studies in the final analysis, of which 9 were RCTs, 1 was a controlled trial and 1 a before and after study. Most studies were conducted in the US (81.9%). Six studies had data on the uptake of influenza vaccination, three on HPV series completion, 1 on PPSV23, and 1 on vaccines recommended for adolescents. In 4 studies email reminders proved to be more effective in increasing vaccination uptake than no reminders. In other four studies, email reminders were compared to reminders delivered via traditional methods (phone call, mail, paper card) and they all failed to prove the superiority of email reminders. On the other hand, four studies compared the effectiveness of email reminders with reminders delivered via other communication technologies, also failing to prove their superiority. In one study a significantly higher increase in uptake was achieved when combining emails with Interactive Voice Response phone calls. Finally, we included four studies that analyzed the content of the email. Conclusions In conclusion, this review outlined that not enough evidence is available regarding the use of email reminders to increase vaccination uptake. Our findings suggest that the choice of reminder method should depend on the population and future studies should analyze its cost-effectiveness and convenience in respect to other methods, and aim at improving the content of emails to increase their efficacy as a reminder method.