In this meta-analysis, 10 out of 13 studies reported an impact in depression, with the overall prevalence reaching 59.7%. Such high prevalence rates can also be observed in student population from other continents. A Chinese study with 746,217 students reported that 45% had probable clinical acute stress, anxiety or depression symptoms. The prevalence rate only for depression was 21.1% ^[19][39]. Wu et al. ^[18][38] reported in their systematic review and meta-analysis, regrouping 66 studies, that the overall pooled prevalence of depression in students was 34.8% (95% CI: 16.4–55.9%). A study on 898 U.S. young adults also reported high levels of depression (43.3%, PHQ-8 scores ≥ 10). The authors found a significant link between loneliness, COVID-19 specific worries, a low distress tolerance and high levels of depression ^[20][40]. Being isolated during a pandemic increases the probability of suffering from depressive symptoms ^[24][44]. This study supports the findings above and partly explains the increase of the prevalence of depression. Similarly, students in China have been recognized as having higher depressive levels during COVID-19 ^[25][45]. Increases in loneliness have also been reported in UK university students ^[23][43], with the authors acknowledging that many students are confined to small rooms with little or no outdoor space, leading to feelings of entrapment. With these results, it can be suggested that Europe has the highest prevalence rate of depression. This may be due to the severity of lockdown rules, the duration of the isolation period, support of the governments or other population/country related aspects.

Lastly, 4 of the 13 identified studies for this meta-analysis focused on the implication of stress with the overall prevalence reaching 47%. Not much less than the European students, Ma et al. ^[19][39] reported that acute stress was the most common problem in Chinese students with a prevalence rate of 34.9%. However, a study on 2059 students from an American university reported that 88% experienced moderate to severe stress, which is almost double that of European students and more than double when comparing with Chinese students ^[26][46]. Qualitative studies support this finding with increased stress caused by lockdowns during the pandemic described by the university ^[22][42]. This is suggested to have greatest impact on first-year students, who were already trying to adapt to commencing university life ^[23][43].

Moreover, in order to explain the high prevalence rates, the literature suggests that quarantines, reduced contact, reduced intimacy and social isolation are related to physical and mental health degradation ^[8][27][8,47]. These restrictions were present for weeks and sometimes months during the lockdown period, with long periods of isolation leading to a loss in connectedness and decreases in university students ^[23][43]. The results of this analysis demonstrate that the number of students developing negative emotional symptoms is increasing, possibly at the expense of mental wellbeing. This will have long-term implications, even after the pandemic, such as low quality of life, anxiety or depression disorders, post-traumatic stress disorder, low general health and cardiovascular diseases ^[28][48]. An increasing demand for psychological help from professionals, due to this increase in negative emotional symptoms, can be expected. Son et al. ^[22][42] called for urgent development of intervention and prevention strategies to support the mental health of university students.

Numerous variables can have a different impact on the situation. For example, students living with their families, having their support and the interaction with them, will most likely have a lower incidence of developing negative emotional symptoms compared to students living alone and away from their beloved ones. Similarly, to ensure for social distancing and minimizing contact, universities decided to switch to online classes. Aside from students feeling disadvantaged by remote learning ^[23][43], this decreases the opportunity to socialize with others, increasing the prevalence of anxiety and depression to a higher level compared to the general population under normal conditions ^{[29][30][31][32][33][34][35][36][37][38][39][40]}[22,23,24,25,26,27,28,29,30,31,32,33].

Limitations

The results of this study have to be interpreted carefully because some studies have very high prevalence rates, which influences the overall pooled prevalence. Likewise, some of the studies have a small sample size that often isn’t representative for the whole student population of that country. In order to regroup as much data as possible from different countries, no difference was made between the levels of condition but between experiencing (yes) or not experiencing (no) symptoms. Since the ‘yes’ data section regrouped the conditions from mild to severe or extremely severe, this partly explains the high prevalence rates. A high level of heterogeneity between studies and major asymmetry was found for all three symptoms which suggests a risk of publication bias. The low number of studies does not include the entire or most of the European continent. Furthermore, some studies of different countries had to be dropped because of their incompatible data, which limited the findings and representation of the situation.