The effectiveness of vibratory stimulation in reducing pain in children receiving vaccine injection: A randomized controlled trial

•The effect of vibratory stimulation on injection pain relief has limited evidence.•A blinded method revealed that vibration did not significantly reduce a child’s pain.•Child who was younger or disliked BUZZY® expressed higher injection pain. Although vaccine injections are important, children experience pain and discomfort upon their administration. BUZZY®, a vibratory stimulation tool with an ice pack, was reported to be an effective tool for reducing the pain caused to children during injection administration; its mechanisms were explained by gate control theory. However, the evidence is inadequate because of insufficient methodology in previous reports. Therefore, we aimed to assess whether the application of vibration would significantly reduce children’s pain during vaccine injections. A single-blind randomized controlled trial recruiting children aged ≤6 years who were receiving vaccine injections was conducted between August and December 2019. If the children’s parents consented to their participation, BUZZY® was attached to the child’s arm prior to vaccination. BUZZY® was switched on before injection in the intervention group but not in the control group. The vaccination procedure was recorded, and researchers and parents assessed each child’s pain using validated pain scales. Researchers conducted their assessment using video data to ensure blinding. Parents were administered a questionnaire after the children’s vaccination. Data were analyzed using the t-test or chi-square test. We analyzed 118 children (intervention group = 62, control = 56). No between-group difference was observed according to the researchers’ assessment (mean score = 6.98 and 7.63, respectively; p = 0.25); however, a significant difference was found based on the parents’ assessment (mean score = 7.39 versus 8.46; p = 0.02). Most responses received to open-ended questions were positive comments for this study. We revealed that the effect of vibration is not significant in reducing vaccine injection pain among children. Further studies are needed to examine the other components of BUZZY®, which include its cooling effect, and the effect of BUZZY® itself in terms of whether children will undergo vaccination without resistance and have reduced trauma related to vaccination.