Aims and objectives: <p>The primary objective was to determine whether virtual reality affects heart rate compared to standard care during childhood vaccination. Secondary objectives included examining heart rate variation according to age and other influencing factors.</p> Design: <p>A randomised controlled clinical trial.</p> Methods: <p>This article presents the secondary findings of a study on the effect of virtual reality on pain and fear in children undergoing vaccination. It was a two-arm trial with 88 in the virtual reality group and 98 in the control group. Heart rate was the primary outcome (measured with a pulse oximeter). Secondary outcomes included pain (Wong–Baker FACES), fear (Children’s Fear Scale), and environmental and sociodemographic variables. Statistical analyses included Chi-squared, Student t-tests, McNemar tests, and a multivariate multiple linear regression model, with significance set at p&lt;0.05.</p> Results: <p>The heart rate increased in both groups after vaccination, with the increase being greater in the control group (5.9 beats per minute difference) compared to the intervention group (3.0 beats per minute), although this difference was not significant (p=0.189). The multivariate regression model showed that increasing age, the presence of the mother rather than any other companion and having simultaneously received multiple vaccinations was associated with a reduced heart rate. </p> Conclusions: <p>Virtual reality is an effective distraction tool in paediatric vaccination which influences physiological responses such as heart rate. </p> Clinical trial registration: <p>Reference number NTC04096833. Date of registration: 18 Sept., 2019</p>