*2.4. Settings and Locations Where the Data Will Be Collected*

The scenario of CZS in Brazil is 3523 confirmed cases, with the Northeast region being the most affected, with 1907 cases. Rio Grande do Norte, where this study will occur, is one of the 9 states in the Northeast region and has 126 confirmed cases of CZS. In the national gross income ranks, it occupies the 17th position among the 34 Brazilian states. In 2010, the Human Development Index of Rio Grande do Norte was 0.684 and ranked 16th among the 27 federative units in the country.

Recruitment of participants will take place through early intervention services, pediatric clinics that provide physical and occupational services, and community-based programs that serve the study populations throughout Rio Grande do Norte (RN) state in Brazil. The recruitment will take place between January and December 2021.

### *2.5. Patient and Public Involvement*

Parents' involvement in the design of the protocol: parents or caregivers of children diagnosed with CZS who received a rehabilitation service at Clínica Escola de Fisioterapia da Facisa—Santa Cruz, RN were asked to answer a questionnaire prepared by the researchers, with 8 questions related to intervention preferences. Initially, the parents watched a video about the Go Zika Go project and then they were interviewed by the first author (EL) at the clinic or at home. The questions included aspects of the families' interest in participating in the intervention, space available at home to use the ride-on car, ideal time for mobility training, preference for the place to perform the intervention, etc. Five parents/caregivers participated in this exploratory stage of the research. The results of this stage

showed that all families were interested in participating in the intervention and stated that the training can be performed at home and/or at the clinic setting.

#### *2.6. Outcomes Measures*

#### 2.6.1. Primary Outcome

The primary outcome of the study will be the feasibility of the protocol, including a narrative description, recruitment and retention rates, adherence and acceptability of the protocol. A mixed methods approach will be used to assess the primary outcome.

A document analysis will determine the number of parents who received information about the study by mail, the number of potential participants contacted by telephone, how many parents met the inclusion criteria and how many provided informed consent, received, and completed the intervention.

Qualitative data will be collected using the photovoice method and focus groups. Photovoice is a participatory action-research modality that uses photographs to express individuals' experiences during their daily realities [23].

Photovoice aims to record and present everyday realities using photography; promote dialogue and critical reflection of reality and know the strengths and weaknesses of the target audience; and reach decision makers [24]. Photovoice will explore families' perception of the feasibility of modified ride-on cars for children with CZS at home and in the community. In the eighth week of the intervention, the parents of children with CZS will be invited to participate in a focus group to provide information about the application of photovoice, its ethical aspects, to clarify doubts about the handling of cameras, expectations in participation and to solve personal issues that may arise. Thus, the methods will follow the Wang and Burris [25] recommendations. Disposable cameras will be offered to record the photos. Parents or caregivers who prefer not to use the camera offered by the researchers will use the cameras on their smartphones and share information by the messaging app. Guidance will be provided on how to capture quality photos, and information about the privacy of people in the scene to be photographed. Parents/caregivers will be instructed to photograph moments of the child's routine at home and in the community. To guide the capture of the photos, parents/caregivers should follow a script of questions asked by the researchers, which include: (1) How does my child feel when using the modified ride-on car? (2) Does the modified ride-on car help my child to get around at home and in the community? (3) Does the modified ride-on car help my child to play with other children? When and where is the modified ride-on car used? Participants will be instructed to capture photos that answer study questions over the next 4 weeks (the third month of intervention). It is recommended that each participant register between 20 and 30 photos [25]. After this period, digital images or printed photographs will be delivered to the research team for the preparation of the second focus group.

In the 12th week of the intervention, the second focus group will be held, where the photos will be displayed and shared with the researchers and other participants, so that the images can be discussed, allowing for a deep reflection from the creation of a proper reading of each moment, on the use of modified ride-on cars by children with CZS at home and in the community. Each participant will be asked to select the most significant pictures representing the experience of their children using the ride-on car. The showed method [26] will be used through its specific questions to facilitate assistance to participants in contextualizing the meaning of their photographs. In addition to the discussion on the contents of the photos, the following feasibility questions guide will be used: What is your perception of the intervention with modified ride-on cars? What helped or hindered your child's use of the modified ride-on cars at home and in the community? Do you think the intervention was useful for your child? All focus groups will be conducted in person by two members of the research team. The sessions will be recorded in audio and video, transcribed and analyzed thematically [27,28].

Quantitative data will be collected from feasibility questionnaires for parents and professionals. The parents feasibility questionnaire (PFQ) [29,30] includes questions related to satisfaction with the intervention, the time of use at home and in the community, the usefulness of the ride-on car, the level

of comfort related to the time of its use and the need for help from others during use. PFQ will be used at the end of week 4, 8, and 12 of the intervention, and at follow-up. The assessment of learning powered mobility (ALP) [31] will be used to measure the feasibility of the intervention. This tool is able to describe the learning process' phase at the initial stages of using a powered mobility device. It also documents the child's occupational performance, thus supporting the selection of learning strategies. Phases are scored from 1 (novice) to 8 (expert) to describe occupational performance while using a powered mobility device, considering five categories: understanding of tool use, level of attention, expressions and emotions, activity and movement, and interaction and communication [31,32]. In this study, the ALP will be applied at the end of weeks 4, 8, and 12 of the intervention, and at the follow-up. In addition, a sociodemographic questionnaire will be used for all participants at the baseline.
