Short message Service reminders to parents for increasing adolescent human papillomavirus vaccination rates in a secondary school vaccine program: a randomized control trial

Purpose: In Victoria (Australia), the human papillomavirus (HPV) vaccine is delivered within a state-wide secondary school vaccine program, administered by local government. This study aimed to test the hypothesis that sending a short message service (SMS) reminder to parents who had consented to their child's receiving the HPV vaccine would lead to greater uptake of the vaccine within the program. The secondary aim was to assess the effect of self-regulatory versus motivational message content in the SMS. 

Methods: A randomized control trial design was used across 31 schools within seven local government areas. Parents of 4,386 consented adolescents were randomized into three study conditions: motivational SMS versus self-regulatory SMS versus no SMS. Follow-up extended beyond the final school visit to the end of the calendar year to capture those who may have attended a catch-up vaccination session. 

Results: On the day of the final school visit, 85.71% of consented students in the control condition received the HPV vaccine, compared with 88.35% (2.64% point increase) in the motivational message condition, and 89.00% (3.29% point increase) in the self-regulatory message condition, χ ² (2, N = 4,386) = 8.31, p =.016. Both intervention messages were similarly effective at increasing vaccination rates. This effect was maintained in the extended follow-up period. 

Conclusions: The trial findings supported the hypothesis that SMS reminders to parents/guardians would lead to greater uptake of the HPV vaccine in adolescents participating in school-based vaccination. Also, this effect was observed whether we used a motivational or self-regulatory message framework. 

Trial registration: Australian New Zealand Clinical Trials Registry (ACTRN12617001307392). Registration Date: September 12, 2017. Retrospectively registered.