This paper reports the results of the 4th survey of the Swiss Corona Stress Study. During the survey period from November 16-28, 2021, 11167 people from all over Switzerland participated in the anonymous online survey. Stress factors: There were major differences between the group of vaccinated persons (58 percent of respondents) and the group of unvaccinated persons in terms of the stress factors associated with the subjective perception of stress. The greatest differences were found in the stress caused by measures such as the certificate requirement, which the majority of the unvaccinated perceived as stressful, while the majority of the vaccinated perceived it as relieving. The burden of conflicts in the family, among friends or at the workplace due to corona measures or vaccination was high among both vaccinated and unvaccinated persons. However, it was significantly higher among the latter. There were also large differences - here with a higher burden among vaccinated persons - in the fear about the health consequences of Covid-19, such as the concern that someone in the closest circle could become seriously ill. Fears of suffering from Long Covid in case of an infection, or that children might bring the coronavirus home and infect parents or grandparents, were also more prevalent among vaccinated than unvaccinated respondents. Among respondents with their own children between the ages of 4 and 11 (a total of 2079 people), only 17 percent among vaccinated parents were not at all afraid that their child will become infected with the coronavirus. Among unvaccinated parents, the figure was 68 percent. Depressive symptoms: The proportion of respondents with moderately severe or severe depressive symptoms (PHQ>=15) was 19 percent, with vaccination status not playing a relevant role. In April 2020 (lockdown), this proportion was 9 percent; in May 2020 (partial lockdown), 12 percent; and in November 2020 (second wave), 18 percent. Risk factors for moderately severe or severe depressive symptoms were:- Young age: Severe depressive symptoms were most common in the youngest group (14 to 24 years old), with a share of 33 percent. Among participants who attended school or college/university, depressive symptoms were most strongly related to stress from pressure to perform at school. - Financial losses: Individuals whose financial reserves decreased during the pandemic were more likely to experience major depressive symptoms (32 percent) than those with unchanged or increased reserves (13 percent). - Previous mental health issues: Individuals with mental health problems prior to the pandemic are more likely to experience major depressive symptoms (34 percent) than individuals who reported having no mental health problems prior to the pandemic (14 percent). Substance use: Among those taking tranquilizers or sleeping pills (3544 persons), 53.6 percent reported an increase, 3.5 percent a decrease, and 42.9 percent no change in use during the pandemic (Figure 4). A similar pattern emerges for persons using nicotine, alcohol, or cannabis. The extent of use of these substances is related to the severity of stress, anxiety, and depression symptoms.