Randomised or quasi-randomised controlled trials of interventions for reducing vaccine-related pain (including pharmacological, psychological, physical or operator-dependant techniques) compared with placebo or sham procedures, usual care or no treatment, were eligible for inclusion in the review. The outcome of interest was self-reported acute pain from the injection.
Interventions in the included trials were topical local anaesthesia, vapo-coolant spray, tactile stimulation, jet injectors, cold needles, and warmed vaccines. The vaccinations given included influenza, hepatitis A and B, diphtheria-tetanus, and unspecified travel vaccines. Pain was measured using visual analogue scales (VAS), the McGill present pain intensity questionnaire (original and modified), a verbal rating scale, and a discrete scale based on pain from previous puncture. Most scales were scored from 0 to 10, except the original McGill present pain intensity scale which was scored from 0 to 5, with a higher score indicating more pain.
The authors did not report how many reviewers performed the study selection.