This single-center, parallel-group, randomized experimental study will compare the effects of two active non-pharmacological interventions - distraction-card use and emotion-regulation toy squeezing - on procedural pain and pain-related fear during intramuscular tetanus vaccination in children aged 4-7 years. Eligible children will be randomized to either the distraction-card group or the emotion-regulation toy-squeezing group. Pain will be assessed using the Wong-Baker FACES Pain Rating Scale, and pain-related fear will be assessed using the Children's Fear Scale before, during, and after the intramuscular injection procedure.

Hypotheses

• H1a: There is a difference between the groups in mean Wong-Baker FACES scores during the procedure.
• H1b: There is a difference between the groups in mean Children's Fear Scale scores during the procedure.

The study is planned as a single-center, randomized experimental trial with two parallel active intervention groups. The study population will consist of children aged 4-7 years for whom intramuscular tetanus vaccination is planned at Mersin University Hospital.

The sample size was calculated using a priori power analysis based on an effect size of d = 0.714 from Ugucu et al. (2022), with alpha = 0.05 and power = 0.80. The final sample is planned as 68 children, with 34 children in each intervention group.

The Pediatric Vaccination/Injection Unit will be arranged to provide the same environmental conditions for all children and parents, including lighting, temperature, noise level, seating, and procedural workflow. It is decorated with cartoon characters and ornaments. Only one child will undergo the procedure in the room at a time. Routine practice will support parental presence during the invasive procedure. The nurse who performs the intramuscular tetanus vaccination will be the same for both groups and children where feasible and will have pediatric clinical experience.

Before the procedure, children will receive an explanation appropriate to their developmental level, and their physical comfort will be ensured. In the distraction-card group, the child will begin using age-appropriate distraction cards two minutes before the intramuscular injection. The child will be actively engaged with the cards through visual attention and simple developmentally appropriate prompts until the injection procedure is completed. In the emotion-regulation toy-squeezing group, the child will begin squeezing an age-appropriate emotion-regulation toy two minutes before the intramuscular injection and will continue until the procedure is completed.

Pain and pain-related fear scores will be recorded by the researchers two minutes before the procedure, during the procedure at needle insertion/vaccine administration, and one minute after the procedure. Data will be collected during the routinely planned intramuscular tetanus vaccination procedure without delaying or replacing standard clinical care.

Data Collection Instruments The Child Information Form, developed after a literature review, will include variables such as the child's age, sex, previous hospitalization and injection/vaccination experience, previous invasive procedure experience, and the presence and frequency of invasive procedure experience in the last week and in the last month.

The Wong-Baker FACES Pain Rating Scale is a valid and reliable measurement tool used to assess acute pain in children older than three years who can communicate. A score of 0 means no pain, and a score of 10 means unbearable/severe pain. According to scoring, 0-4 indicates mild pain, 5-6 moderate pain, 7-8 severe pain, and 9-10 unbearable pain. The approximate administration time is two minutes. Permission to use the scale should be documented before data collection if required.

The Children's Fear Scale assesses pain-related fear in children. The scale consists of five drawn facial expressions scored from 0 to 4, ranging from a neutral expression (0 = no anxiety/fear) to a fearful face (4 = severe anxiety/fear). Scores of 2 and above are commonly interpreted as high fear in the source methodology. The approximate administration time is two minutes. Permission to use the scale should be documented before data collection if required.

Statistical Analysis Plan Data will be analyzed using a statistical package program. The level of statistical significance will be set at 0.05. The Kolmogorov-Smirnov test will be used to assess the normality of dependent variables. Chi-square tests and tests comparing means will be used to determine group similarity. Appropriate parametric or non-parametric tests will be used to compare between-group and within-group means depending on whether the distribution is normal. If differences are found between group means, an effect size appropriate to the test family will be used.

Randomization and Allocation Concealment Block randomization will be used to preserve balance in participant numbers between groups. The randomization list will be generated by an independent statistician using simple random selection through randomizer.org or equivalent computer-assisted randomization. After block randomization, sequential numbers will be placed in closed opaque envelopes to conceal allocation.

Ethics, Consent, and Assent The study will begin after obtaining ethics committee approval from the Mersin University Health Sciences Research Ethics Committee, written institutional permission from the relevant hospital/unit, written informed consent from parents/legal representatives, and verbal assent from children when developmentally appropriate.

Inclusion Criteria:

• Child aged 4-7 years
• Child with need or plan for intramuscular vaccination

Exclusion Criteria:

• Child with a neurodegenerative disease, mental retardation, vision and hearing problems, chronic, life-threatening (sepsis, shock, respiratory / cardiac arrest) or genetic disease
• Child with use of opioids, narcotics, analgesics or sedatives in the last 24 hours before the procedure

There is not a plan to make IPD available.

The children and their parents will be blinded to the groups. The principal researchers (R1, R2) will be blinded to the research hypotheses. The opaque envelopes are stored in a locked cabinet by the researcher who performed the randomization. Data entries will be performed using the codes A and B. Codes will be shared with the researchers after statistical analyses are conducted and the research report is written.