**1. Introduction**

Isolation and quarantine measures (used or experienced) during epidemics generate separation and restriction of human movement, imposing drastic changes in routine and the need for adaptation at a time of great physical, social, economic and psychological vulnerability. Despite all the efforts towards containing the spread of the disease, isolation and quarantine measures come with psychological costs to individuals and, therefore, some care and attention related to mental health must be provided [1–7]. The World Health Organization declared the new coronavirus disease (COVID-19) a pandemic on 11 March 2020. At the end of that month, due to the rapid increase of cases (or infections), Brazil declared a mandatory quarantine, excluding essential service workers.

The psychological consequences of quarantine and isolation measures have already been identified in previous epidemics such as SARS [8–11], Ebola [12,13], and H1N1 [14,15]. So far, most of the scientific information on the impact of the SARs-CoV-2 pandemic on mental health has been presented as letters to editors or brief reports from experts due to the ongoing nature of the pandemic and little data is available. The existing documents indicate that the current quarantine and mass social isolation can have concerning psychological effects [3,5–7,16]. As of July 2020, there were few published epidemiological studies focusing on the Chinese population, with some assessing the effects of the disease from a clinical point of view, including mental health in patients who contracted the disease [17,18] and the mental health effects on frontline healthcare workers highlighting their vulnerable situation [19,20]. Only four studies evaluated the mental health conditions on the general population—three from China and one from Brazil.

Gao et al. [21] investigated 4827 Chinese adults and reported a high prevalence of depression (48.3%), anxiety (22.6%), and concomitant depression and anxiety (19.4%). Wang et al. [22] reported that 16.5% of the 1210 Chinese respondents had symptoms of moderate to severe depression, 28.8% had severe anxiety, and 8.1% had moderate to severe stress levels. Figueiras et al. [23] carried out a study with 1460 Brazilian adults and reported that women, younger people, and those with less education had higher levels of depression and anxiety. The authors also describe behaviors of individuals during quarantine and their relationship to depression, anxiety, and stress symptoms. However, none of these studies evaluated a nationwide population. To date, only one nation-wide study has been carried out in China by Qiu et al. [24] with 52,730 participants from 36 provinces that found that peri-traumatic stress was related to sex, age, educational level, region of residence, local health structure, and being a migrant worker. Nevertheless, some areas of that large country were not included in the study.

The literature on COVID-19 is increasing in an exponential rate. Scientists around the world have been making efforts to understand the pandemic from different aspects. However, everyone has the same challenge, which is to provide quality responses as quickly as possible to the population. Science is being carried out in real time. In early September 2020, four more studies involving a general population sample (one Italian study [25], one Israeli [26], one from the United States [27] and one from United Kingdom [28]) were published with mental health data in the pandemic. Moccia et al. [25] conducted a study with 500 adults in the initial phase of the outbreak of SARs-CoV-2 in Italy (April). Of the participants, 62.0% reported not having psychological distress due to the pandemic, 19.4% had mild distress and 18.6% had moderate or severe, with women being the most affected. Individuals with cyclothymic, depressive and anxious temperaments were more likely to have moderate or severe psychological distress. Palgi et al. [26] conducted a study with 1059 adults to evaluate symptoms of depression and anxiety related to the SARs-CoV-2 pandemic in Israel. Most of the participants were women and had a high level of education. The youngest were more vulnerable to depressive and anxious symptoms and there was no relationship between these symptoms and the existence of pre-existing chronic diseases. Loneliness caused by isolation measures was the most prominent risk factor for the development of depressive and anxious symptoms.

Bruin [27] investigated the relationship between age and perceptions of risk, anxiety and depression during the pandemic in the United States. Data collection was carried out in March and 6,666 North American adults participated (52% women with an age range from 18 to 100 years [mean = 48.6; standard deviation = 16.6]). Older individuals had a greater perception of the risk of dying if they were infected with SARs-CoV-2, greater awareness that being in isolation reduces the risk of contagion and were less likely to have depression and anxiety.

To date, the UK study [28] appears to be the only longitudinal study that assessed changes in mental health in adults before and during the pandemic lockdown. The authors used data from the UK Household Longitudinal Study (UKHLS) which started in 2014, with surveys carried out at the beginning (for example, 1 January 2014) and at the end of two years (for example, 31 December 2015) with annual overlap. 15,376 individuals over the age of 16 from Wales, Scotland, Northern Ireland, and region of England participated. The mental distress increased from 18.9% (in 2018–2019) to 27.3% one month after the lockdown (April 2020). The current mean score for non-specific mental distress in the population was above expectations considering the estimated trend from 2014 to 2018. This increase was significantly higher among younger people, women, those with lower economic status and people living with children.

In a few days, new studies have been published with regards to the mental health impact during the COVID-19 pandemic. Among the recent studies, there is a systematic review/meta-analysis published by Salari et al. [29] thatincluded 17 studies from 10 different countries. Among themost common psychological symptoms related to epidemics are post-traumatic stress [14], anxiety, and depression [1,4,6,22], which can be found during the isolation/quarantine period and can outlast the epidemic. Brooks et al. [1] highlight that this is due to the presence of specific stressors including the duration of the quarantine, fear of being infected, frustration and anger for the loss of the normal routine and reduction of physical and social contact, inadequate supply of food, water or accommodation, and confusing or inadequate information coming mainly from government and public agencies. Among the post-pandemic stressors, financial difficulties and social stigma towards infected individuals and health care workers are mentioned.

With a pandemic scenario, all individuals, to a greater or lesser degree, will depend on their mental resources to cope with the lifestyle changes, fears, and uncertainties. As the SARS-Cov2 pandemic, combined with the political and economic impact, imposes a new and distressing context, the monitoring of the population's mental health may contribute to establish individual or collective strategies of support, guidance, prevention, and intervention to minimize mental trauma during and after the pandemic. Still, Sani et al. [16] emphasize that the identification of possible predictors for the psychological impact of the pandemic on populations can be relevant for the elaboration of more targeted and resolute intervention plans.

This nationwide study was carried out to assess aspects related to the mental health of the Brazilian population during the coronavirus pandemic. The prevalence of depression, anxiety and stress symptoms and their relationship with demographic and context-related characteristics was verified.

We hypothesized that the prevalence of psychological symptoms is high in Brazil in view of sanitary, economic and political insecurity. We also hypothesized that younger people, women, people with previously diagnosed mental disorders and those most exposed to pandemic news are more likely to develop symptoms of depression, anxiety and stress and be psychologically impacted.
