**9. Limitations of the Study**

One of the major limitations of this study is that the respondents involved in this study (*n* = 2172) were only Polish students; therefore, these results cannot be generalized to other nationalities, racial, or ethnic groups. Among them, the majority of the respondents were females (*n* = 1585) and medical students (*n* = 1314). Therefore, it is hard to establish the obtained results as generalizable because the group of students involved in this study was slightly limited.

The reliability of the results was also limited by the fact that the study was conducted in the form of an online survey where the researchers could not assess the reliability of the information provided by the respondents. Moreover, the other limitation is that the students who fulfilled our survey were only those who were interested in the potential consequences of the COVID-19 pandemic on mental health, had access to the Internet, and were simply interested in taking part in such an online questionnaire.

Besides, it should be taken into consideration that the comparison of our results with other countries (Spain, India, China, and Bangladesh) based on the DASS-21 scale should be analyzed with caution since there might be many potential reasons for any differences between those countries including cultural bias of reporting on mental health.

Another limitation is the fact that the results of the obtained study reflect the wellbeing of students only during the few days when the survey was conducted without any insight into longitudinal effects on students' mental health. On the other hand, the mental health status and psychological symptoms of the respondents before the COVID-19 pandemic were unknown to the researchers, which was associated with the potential difficulties in the interpretation of the obtained results as well.

Taking all the above facts into consideration, it must be stated that the obtained results cannot be assigned to the entire population of Polish students due to the profile of the student who most often completed the survey, the form of the survey which was carried out as an online questionnaire, and the time in which it was conducted that only reflect the well-being of Polish students in the short and particular period of the pandemic. It would be beneficial to perform further studies, especially longitudinal ones, which could provide a clearer understanding of the pandemic effect on students' depression, anxiety, and stress levels.
