**4. Discussion**

A second mental health pandemic is likely to coexist with the COVID pandemic. Nursing staff appear to be particularly vulnerable to the pressure created by the pandemic situation; especially the female population who exhibited higher values of burnout and depression but also lower values of coherence. Scientific studies indicate stronger SOC scores among males compared with females [38,39], but also suggest the dynamic impact of age on SOC [38]. In our sample the female population is significantly younger than males, possibly explaining, in part, the difference in SOC scores, assuming age serves as a confounding variable. Furthermore, research argue that men and women are differentially affected by stressors and make different use of their coping resources [40].These findings are consistent with reviews and meta-analyses indicating that female nurses are more vulnerable to adverse mental health effects; facts that should be taken into consideration in further research on stress, coping, and health [4,41,42].

High rates of burnout and depression in health care workers are a consistent finding in studies worldwide even before COVID-19 [28,43,44]; the pandemic crisis has highlighted the problem. The increase in burnout may be due to the high pressure exerted on hospitals by the pandemic [4]. At the time of the study, cases and admissions to Greek hospitals were on the rise, while work leave for healthcare staff had been suspended for the preceding five months.

In the given period the mental health of the healthcare personnel is especially important for the society as a whole. Firstly, because it has a decisive effect on the quality of

health services as mentioned in several studies [45] and, secondly, because it can affect the relationship of public trust in the healthcare system; a factor particularly important in ending the pandemic.

The association between burnout and depression was confirmed in the present study. This correlation (r = 0.66), although being strong, cannot justify an overlap of burnout and depression. The interpretation of the variation of depression from burnout at 43.7% leaves the issue open. Mediation analysis identified burnout as a contributing factor to depression. We would, therefore, prefer to adopt the suggestion given by the World Health Organization, which recognizes burnout as a separate entity, both in International Classification of Diseases (ICD)-10 and ICD-11, giving the code Z 73.0, i.e., as a factor that affects health but not as a separate disease. It is of interest to point out that only one European country has recognized burnout as an occupational disease [46].

The results of the study identify SOC as the negative moderator of the relationship between CBI and BDI. Recent studies highlight the role of SOC in mental health during the pandemic. In particular, a study conducted in eight countries found that a weak SOC was associated with an increased likelihood of "potential depression or anxiety disorder" [47]. A similar result was found in adult samples from Italy [48], and also from Germany [49]. The authors of the latter work explicitly recommended interventions aimed at strengthening the SOC in vulnerable individuals.

Alternatively, interventions have been suggested that use cognitive-behavioral techniques to help people find ways to overcome negative thought patterns and change the way they respond to things that make them feel anxious or upset. Such interventions may include self-help management techniques (e.g., online cognitive behavioral therapy—CBT) [50].

In conclusion, we would like to point out that psychological interventions cannot and should not conceal the real shortcomings of a health system. The theoretical basis of the SOC is to explain why despite the great pressure exerted on them, there were nurses who did not experience burnout and/or depression. The health system is responsible for alleviating the imposed pressure by providing staff with appropriate working conditions, such as adequate supplies and equipment (e.g., PPE), an appropriate patient–nurse ratio, and a work schedule that ensures sufficient rest.

Finally, we will reiterate the message from the World Health Organization for health workers, warning that managing mental health and psychosocial well-being during this pandemic is as important as managing physical health.

The current research was carried out during the COVID-19 pandemic. Therefore, to follow pandemic instructions, data were collected with the online method instead. This meant that nurses without internet access could not participate. Subsequently, the collected data do not represent such groups' considerations and influences the study's generalizability. Additionally, the self-reported data were subject to common method biases. Moreover, owing to the periodical rotation of the nursing personnel, contextual factors relating to the unit where the nurses worked were not included in data collection. Finally, the study was cross-sectional. Therefore, causality between the study's variables cannot be determined.

#### **5. Conclusions**

We evidenced high rates of depression and burnout in nursing staff. Mediation analysis highlighted burnout as a factor influencing depression, while sense of coherence functioned as a negative moderator between burnout and depression. Psychological, as well as administrative, interventions are necessary to be implemented immediately to address the problem.

**Author Contributions:** Conceptualization, A.P. (Argyro Pachi), A.T., C.S.; methodology, A.T., I.I., A.P. (Argyro Pachi); software, A.T., I.I. and A.P. (Aspasia Panagiotou); validation, A.P. (Argyro Pachi), S.Z., M.T.; formal analysis, A.P. (Argyro Pachi), A.T., I.I.; investigation, C.S., A.T.; resources, A.P. (Argyro Pachi); data curation, A.T., I.I., L.A.T., A.P. (Argyro Pachi), S.B.; writing—original draft preparation, A.T., A.P. (Argyro Pachi); writing—review and editing, A.T., C.S., A.P. (Argyro Pachi); supervision, A.T., A.P. (Argyro Pachi); project administration, A.T., A.P. (Argyro Pachi). All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** The study was conducted in accordance with the Declaration of Helsinki, and approved by the Clinical Research Ethics Committee of "Sotiria" General Hospital (Number 12253/7-5-20) and from the Ethics Committee of the University of Peloponnese (18 January 2021).

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study since the first page of the electronic questionnaire clearly stated that the completion and submission of the questionnaire was considered a statement of consent. Participation in the research was voluntary.

**Data Availability Statement:** The data and the questionnaires of the study are available upon request from the corresponding author.

**Acknowledgments:** We would like to thank all participants in our study.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

