Preventing Postvaccination Presyncope and Syncope in Adolescents: A Randomized Controlled Trial of a Clinic-Based Intervention
Using a vibration-and-cold device plus video games reduced post-vaccination presyncope in 10–14-year-olds.
*Randomized controlled trial; Level 1b (OCEBM).
*Randomized controlled trial; Level 1b (OCEBM).
Citation
Smith MJ, Harrington TA, Chung RJ, et al. Preventing postvaccination presyncope and syncope in adolescents: A randomized controlled trial of a clinic-based intervention. The Journal of Pediatrics. 2026;293:115035. Trial registration: NCT04772755.
Background
Fainting after vaccines is uncommon but can cause injuries; near-fainting symptoms are more common and may signal risk. Pain and anxiety may contribute, so simple clinic tools might help.
Patients
Adolescents aged 10–14 years receiving at least one intramuscular vaccine at one health system’s primary care clinics. Most common exclusion: receiving a COVID-19 vaccine.
Intervention
A vibration-and-cold pack placed near the injection site plus playing a tablet video game during vaccination.
Control
Usual care (participants were not prevented from using their own phones).
Outcome
(Primary) Presyncope during 20-minute observation, based on any self-reported near-fainting symptom; (secondary) pain on Wong-Baker Faces Pain Scale (0–10).
Follow-up Period
20 minutes after vaccination (pain also at 1–3 and 10 minutes).
Results
| Outcome | Intervention | Control | Effect |
|---|---|---|---|
| Presyncope (primary) | 36% | 48% | Absolute risk reduction 12%; NNT=9 |
| Pain at 1–3 minutes (0–10) | Mean 2.51 | Mean 3.26 | Mean difference −0.75 |
| Pain at 10 minutes (0–10) | Mean 1.09 | Mean 1.54 | Mean difference −0.45 |
Analysis was modified intention-to-treat. No syncope occurred in either group.
Limitations
Single-site, open-label study. The combined approach cannot separate the device’s effect from distraction. Presyncope relied on self-reported symptoms (including mild symptoms), and the clinical importance of a 12% reduction may be modest. COVID-19 vaccinations were excluded, limiting generalizability.
Funding
Centers for Disease Control and Prevention contract; funder involved in study design and reporting.
Clinical Application
For 10–14-year-olds getting routine vaccines, consider vibration-and-cold plus game distraction to reduce near-fainting symptoms; benefit is modest and may best fit higher-risk patients.
Discussion
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In this open-label randomized controlled trial, Buzzy plus a tablet video game reduced postvaccination presyncope from 48% to 36% (absolute risk reduction 12%, NNT≈9). Given the self-reported presyncope outcome (and no syncope events), how confident are you in internal validity, and would you adopt this in routine adolescent vaccination visits? In this randomized trial, presyncope occurred in 48% of controls vs 36% with the combined Buzzy + video game intervention. Which option correctly states the absolute risk reduction (ARR) and the approximate number needed to treat (NNT)?