Related Experiment Video
Updated: Jun 9, 2026
Systematic Assessment of Well-Being in Mice for Procedures Using General Anesthesia
Published on: March 20, 2018
A Systematic Review and Meta-Analysis of the Effectiveness of Procedural Interventions for Reducing Distress During
Anna Taddio1,2,3, Vibhuti Shah4,5, C Meghan McMurtry6,7,8
1Professor, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON.
Background:
This systematic review was conducted as part of a 10-year update to a clinical practice guideline about reducing distress during vaccine injections and evaluated procedural interventions (injection techniques) that clinicians and organizations can use. Altogether, 4 clinical questions were included: (1) no aspiration before injection; (2) fast injection; (3) injecting the vaccine causing the most distress last; and (4) reducing fear cues before injection.
Methods:
Panel members voted on clinical questions and outcomes, as per GRADE methodology. A search strategy was executed across 5 databases: MEDLINE, EMBASE, APA PsycINFO, CINAHL, and ProQuest Dissertations. Randomized and quasi-randomized controlled trials involving individuals undergoing vaccination across the lifespan were eligible and identified in a stepwise fashion involving at least 2 reviewers. The critical outcome was distress, assessed by vaccine recipients or observers. Data were combined using standardized mean difference (SMD) with 95% CIs. Summary statements were developed according to certainty of evidence and magnitude of effect (threshold SMD ≥0.2).
Results:
Altogether, 12 studies were included. Meta-analysis of 6 trials indicates that injecting without aspiration may result in a reduction in distress (SMD=-0.77, low certainty), as reported by vaccine recipients and observers. Fast injection may reduce distress slightly, according to self- and observer-report in 2 trials (SMD=-0.27, low certainty). Injecting the vaccine that causes the most distress last likely reduces distress (SMD=-0.73, moderate certainty), as reported by observers in 4 included trials. One trial providing indirect evidence demonstrates that reducing fear cues may reduce distress (SMD=-0.26, very low certainty), but the evidence is very uncertain.
Conclusions:
Procedural interventions are associated with benefits for vaccination-related distress and provide feasible options for clinicians and organizations to improve the vaccination experiences of vaccine recipients.
