*3.2. Study Design and Sample*

The research has been carried out in collaboration with health personnel working in hospital centers in Spain, mainly nurses, physicians, and nursing assistants. The subjects studied were 157. The period in which the questionnaire was administered was between April 6 and 19, in the middle of the confinement stage and where daily deaths and active cases of contagion reached their peak in Spain. Although the sample can be considered small compared to other studies, the need to carry out this research at this historical moment made the benefits greater than the disadvantages. For this reason, it was not possible to carry out research based on a representative sample adjustment in the whole of Spain, but rather an intentional cut-off methodology was followed.

To gain access to health professionals who worked directly with patients affected by COVID-19, representatives of workers, hospital and ICU staff from different Spanish hospitals were contacted directly, who facilitated contact with the workers under study. For this reason, the sample is smaller than what could have been obtained by extending the research to all health professionals. In any case, this methodology made it possible to previously select the subjects who were really working with the disease during this period. Subsequently, an online survey was administered through the application of the University of Murcia (umu.encuestas) to which the participants had access without putting their security at risk, and always guaranteeing their confidentiality and anonymity. Participants must accept the ethical conditions and give their consent before accessing the questionnaire and sending their answers.

In any case, all the requirements of the Ethics Committees that Spanish universities establish for their researchers were followed. Since this is a descriptive study in Spain, the approval of a specific Ethics Committee was not required (unlike studies based on experiments). Despite this, the Codes of Good Practice for Research on Human Beings were followed. Furthermore, it is important to add that the participants gave their informed consent in accordance with the Declaration of Helsinki. The project was registered and signed by the research team with the code number REPRIN-PEM-010.

The research design was a simple random sampling in view of the difficulties aroused from accessing health professionals in such a short period of time-due to the phase of confinement in which the Spanish population found itself after the state of alarm decree—and the need to obtain relevant data on this social phenomenon in such an important historical context.
