The intervention, known as the Health-Friendly Programme, took place at the Clinical Skills and Simulation Centre of the Public University of Navarre. The intervention consisted of showing the children different scenarios that simulated various medical contexts, letting them experiment with the material and ask questions.

The structure and content of the intervention were intended to address two main issues. First, the health contexts with which school-age children may come into contact with; these are a consultation at a health centre and a hospital room. Second, the concerns, in relation to intrapersonal, procedural, environmental and interpersonal aspects, experienced by children when they interact with health care professionals or they are sick.

As reference material, the intervention is described in detail in the guide about the Health-Friendly Programme (Escalada-Hernández et al., 2021).

Participants in this group continued with normal activities at school and at home, just like the intervention group, so that the only difference between the two groups was taking part in the intervention. Once the post-study data had been collected from all participants, the participant in the control group also took part in the intervention, a few days later.

The intervention, known as the Health-Friendly Programme, took place at the Clinical Skills and Simulation Centre of the Public University of Navarre. The intervention consisted of showing the children different scenarios that simulated various medical contexts, letting them experiment with the material and ask questions.

The structure and content of the intervention were intended to address two main issues. First, the health contexts with which school-age children may come into contact with; these are a consultation at a health centre and a hospital room. Second, the concerns, in relation to intrapersonal, procedural, environmental and interpersonal aspects, experienced by children when they interact with health care professionals or they are sick.

As reference material, the intervention is described in detail in the guide about the Health-Friendly Programme (Escalada-Hernández et al., 2021).

Medical fear was measured using the revised version of the "Child Medical Fear Scale" (CMFS-R), in its validated Spanish version. The scale has 17 items with statements on fear of certain aspects related to the healthcare environment, that the children answer according to a three-point scale (0 = no fear, 1 = some fear and 2 = very frightened). The maximum total score on the scale is 34 points. The Spanish validation confirmed the existence of the 4 dimensions identified in the original CMFS-R scale: intrapersonal, procedural, environmental and interpersonal fears