1. Introduction

The COVID-19 pandemic officially declared in March 2020 ^[1] is both “an epidemiological and psychological crisis” ^[2]. Aside of the harmful physical effects that the sickness may cause in infected patients, three collateral factors contribute to an unprecedent worldwide mental health burden in both infected and non-infected people: preventive isolation measures taken worldwide (i.e., lockdowns); drastic changes in daily life (i.e., deceased relatives, overflowed frontline workers, social distancing, curfews) and COVID-19 and Post COVID-19 related psychological symptoms. The purpose of the present manuscript is to summarize the most updated accumulated knowledge so far (January 5^th 2022) about the psychological impact of each factor. Importantly, given the overwhelming number of studies, a broaden vision has been prioritized by selecting systematic reviews, meta-analysis and longitudinal research over cohort, transversal or nation-specific studies, whenever possible. In those cases where the broaden vision also implied citing a vast number of studies, due to space restrictions, two selection criteria has been applied: chronological order of publication (first-year pandemic stage: March to December 2020 and late pandemic stage: from January 2021 on) to illustrate any potential longitudinal tendency, and the affiliation of the authors (citing at least one study per continent, if any) to illustrate any potential cross-cultural difference. Despite the efforts invested to avoid a Western vision of COVID-19 and its psychological impact, this entry may lack of cultural diversity due to the low publication rate of low-income countries.

2. Lockdowns

The characterization of COVID-19 as “pandemic” by the World Health Organization (WHO) in March 2020 ^[1] entailed several nationwide public health measures, among which unprecedent lockdowns in recent decades took place. Lockdowns can be defined as the confinement of specific or general groups of population imposed by certain authority during a given time aiming to reduce the spread of some disease as well as to attenuate the hospital pressure originated by the above-average healthcare demands that the disease causes (the so-called “buy time” measure ^[3]) ^[4]. During the lockdowns, the confined population’s outdoor movements and activities are restricted, which usually entails a general closure of non-essential businesses and establishments. Therefore, the psychological wellbeing associated to the maintenance of rewarding events (such as relative visits, trips, or outdoor leisure time), or routines (such as going to school/work or shopping) can be dramatically reduced.

The psychological impact that the lockdowns might cause in the population had no previous modern referent because there are no historical records of previous simultaneous worldwide strict confinements during the last century. The most resembling lockdowns might be the public actions taken during the two influenza pandemic across the XX century, however they were not regularly adopted nationwide; varied in intensity -from lazarettos to border closures-, and did not happen coordinately with other nations nor in an instant-globalized-Internet-based world, see ^[5] for a revision of quarantines since Middle Age times. There is also little evidence of prior measurements of the psychological impact of more than three months of confinement. The closest study available was a rapid review published some days before the pandemic characterization listing the evidence about psychological impact of recent regional quarantines of a maximum of 21 days caused by SARS, Ebola, H1N1 influenza and Middle East respiratory syndrome ^[6]. They found that symptoms were “wide-ranging, substantial and can be long-lasting” (p. 919) and provided six suggestions to ameliorate them: keeping the lockdowns as short as possible; giving much information; providing adequate supplies; reducing boredom and improving communication; paying especial attention to health-care workers and appealing to altruism.

After COVID-19 lockdowns, research about psychological impact concluded that fortunately, the lockdowns themselves seem not to have contributed to produce significant psychological impact in general population: a recent metanalysis found that their magnitude was “small and highly heterogeneous, suggesting that lockdowns do not have uniformly detrimental effects on mental health and that most people are psychologically resilient to their effects” ^[7] (abstract). Indeed, suicide rates did not rise during house confinement, as a time-series analysis from 21 countries showed ^[8]. However, optimism should not prevent for further strategies, because the return after lockdowns can have a rebound effect and some authors suggest to remaining cautious and vigilant, especially with regards to suicide ^[9][10]. Moreover, even when at a general level the psychological impact of lockdowns was low, for certain vulnerable sectors of population was severe, such as child and adolescents ^[11], subjects with autism spectrum ^[12], pregnant women ^[13], homeless people ^[14], people in poverty, migrants and refugees ^[13], to name a few. As a future lesson, researchers suggest that using common psychological impact measures in different samples would benefit further cross-cultural comparison [i.e., ^[6]] (see below “Pandemic life” for a list of the most used instruments to measure each disorder).

Behaviours with associated negative psychological consequences changed during lockdowns, especially those related to addiction. Whereas a metanalysis about alcohol consumption revealed that the average intake did not vary significantly, it did within subsamples with some previous mental health/alcohol-related risk factors ^[15] or those who were already chronic/excessive consumers, as a four-year longitudinal study showed ^[16]. The same happened to gambling: although bets decreased across countries, in some subsamples problematic gambling was increased ^[17]. This evidence shows that people with previous vulnerable factors should be especially protected in times of significant life adversity, such as international emergency health crisis. Also, crimes that cause relevant psychological impact, such as domestic violence, intrafamiliar sexual abuse, production and demand for child sexual exploitation material, online-grooming and cyberbullying increased worldwide during lockdowns because the confinement led to permanent contact between offenders and victims as well as it led to higher rates of unsupervised Internet connection between children. In this sense, there is evidence of a worldwide increase in domestic violence cases, as systematic reviews report ^[18][19], as well as an increase of calls to domestic violence helplines ^[20] so that more than fifty countries integrated prevention and response to violence against women and girls into COVID-19 response plans, as the United Nations Data Platform shows ^[21]. Multiple international voices raised concern about the need for child protection at home due to the high risk of violence against them [i.e., ^[22]] and data showed that child sexual exploitation material demand raised ^[23].

The return to regular life after lockdown has been associated with the folk syndrome coined “cabin fever”, describing “a combination of anxiety, lassitude, irritability, moodiness, boredom, depression, or feeling of dissatisfaction in response to confinement, bad weather, routine, isolation, or lack of stimulation” ^[24]. However, this folk syndrome has no correspondent official nosologic entity nor there is evidence to be concerned about any public emergency. Indeed, according to the WHO, the unique psychological impact officially recognized as being related to COVID-19 measures is the “pandemic fatigue”. Pandemic fatigue describes “demotivation to follow recommended protective behaviours emerging gradually over time and affected by a number of emotions, experiences and perceptions, such as complacency, alienation and hopelessness. It is an expected and natural response to a prolonged public health crisis – not least because the severity and scale of the COVID-19 pandemic have called for the implementation of invasive measures with unprecedented impacts on the daily lives of everyone, including those who have not been directly affected by the virus itself” ^[25] (pp. 4-7).

3. Pandemic Life

Living life during the COVID-19 pandemic entails adapting to different preventive measures and both the interpersonal and financial consequences of the virus spread. The meta-analysis reviewing the impact that the COVID-19 pandemic has in mental health mostly focus on three disorders: anxiety, depression and post-traumatic stress. These studies usually differentiate the sample evaluated between general population and frontline workers since the latter have been more exposed to contagion, traumatic images and have experienced an overwhelming working load. Within the different jobs considered among frontline workers, health care workers have been the most studied professional group so far. Next, there is a summary of the accumulated knowledge about anxiety, depression and post-traumatic stress across three different sections and within each section there is specific mention to studies with samples of health care workers.

3.1. Anxiety

During the COVID-19 pandemic, different national preventive measures and international recommendations have applied: from general closure of non-essential businesses and establishments to time restricted openings, curfews and travel restrictions; from mandatory vaccination to some population sectors and face mask use to periodic handwashing and ventilation. This situation forces people to flexibly adapt to new scenarios, remain alert about the spread of the virus and sometimes lose previous income levels. Moreover, the news remain as the main source of information for general population, usually updating daily about new viruses variants, preventive measures, legal changes or providing data upon economic impact and death and incidence rates. This situation helps people to be informed as well as makes them constantly alert about the spread of the virus. Consequently, the modification of regular civil life under the feeling of uncertainty; the constant need to be alert; the economic instability with large-scale job loss and the permanent information about contagions and death, within this new uncontrollable situation may contribute to the emergence of anxiety disorders.

A study reviewing research that provided pre- and post-COVID-19 prevalence of mental health burden across 204 countries reported that after one year of COVID-19 pandemic, there is a 25.6% global increase of the prevalence of anxiety disorders, namely, an additional 76.2 million (64.3 to 90.6) estimated cases ^[26]. Even when there are countries lacking data, these numbers reveal a high global psychological impact that can potentially impact mental care systems. With regards to health care workers, systematic reviews and meta-analysis found that this professional sector had higher level of anxiety compared to general population: 24% ^[27] (November, 2020), 34.4% ^[28] (December, 2020) from 8.5% to 13% ^[29] (January 2021), and, in all cases, constantly higher in Western than Asian professionals ^[30] (May 2021), whereas other authors suggest higher rates in Middle-East ^[31] (March 2021).

The most at-risk of suffering from anxiety disorders (both onset or increasing pre-existing symptoms) are people with Obsessive-Compulsive symptoms, such as concerns about becoming contaminated themselves, fear of unknowingly spreading contamination and causing harm to others, overestimation of threats and tendencies to seek reassurance by excessive searching for news on COVID-19 ^[32]. Unfortunately, for all of them, living surrounded by necessary guidelines and signage on hygienic measures about how to prevent the virus spread, such as periodic hadwashing, can reinforce their obsessive ideas. Moreover, doomscrolling, or spending an excessive amount of screen time devoted to the absorption of negative news ^[33], may also approach high rates within the pandemic.

Finally, and for further research purposes, the instruments more employed to measure anxiety found in the meta-analysis and systematic reviews are, in alphabetical order: DASS-21: Depression Anxiety Stress Scale; GAD: General Anxiety Disorder; HADS: Hospital Anxiety and Depression Scale; HAMA: Hamilton Anxiety Rating Scale.

3.2. Depression

During the COVID-19 pandemic, the number of contagions and deaths has constantly increased, varying periodically from curve deflations to exponential peaks. This situation has led people to lose beloved ones, or even suffer themselves COVID-19 health issues with long-term sequelae. The pandemic has also led to the reduction of rewarding activities and fueled negative further perspectives about the future due to financial loss, recurrent new contagion waves and inability to schedule outdoor activities with months in advanced, which may contribute to depressive mood.

Within the aforementioned study reviewing research that provided pre- and post-COVID-19 prevalence of mental health burden across 204 countries after one year of COVID-19 pandemic, it is reported that there is a 27.6% global increase of the prevalence of depressive disorders, namely, an additional 53.2 million (44.8 to 62.9) estimated cases ^[26]. With regards to health care workers, systematic reviews and meta-analysis found that this professional sector had higher level of depression compared to general population: 25% ^[27] (November, 2020), 31.8% ^[28] (December, 2020), from 9.5% to 12.2% ^[29] (January 2021) and 23% ^[30] (May 2021).

A revision of psychological consequences of relatives caused by losing beloved ones after being in Intensive Care Unit (ICU), which is the treatment of choice for severe COVID-19 patients, estimated that “the number of cases of complicated grief following COVID-19 deaths may virtually reach the number of overall COVID-19 deaths” ^[34] (p.3). Therefore, one of the most at-risk group of suffering from depression may be those who lost relatives because of COVID-19 disease. Also, despite the rates of suicide seemed to decreased during the first months of the pandemic ^[8], research community suggests being vigilant to these group of population ^[9].

Finally, and for further research purposes, the instruments more employed to measure depression found in the meta-analysis and systematic reviews are, in alphabetical order: CES-D: Center for Epidemiologic Studies Depression Scale; DASS: Depression Anxiety Stress Scale; HADS: Hospital Anxiety and Depression Scale and HAMD: Hamilton Depression rating scale.

3.3. Post-traumatic stress

The population has witnessed (first-hand or through public information) both COVID-19 related dramatic images, such as accumulated coffins of COVID-19 deceased patients, intubated patients, and threatening behaviours, such as actions specifically associated to situations of emergency conducted by peers (i.e., non-perishable stockpiling; panic buying). All this together with the constant threatening of being infected may be strong enough to meet the criteria for traumatic events, given their uniqueness and because witnesses may feel their life is at risk.

Indeed, metanalysis conducted early after the pandemic characterization found that one-in-four adults ^[35] or a similar 20% (95% CI: 14–25%, p<0.001) ^[36] experienced significant traumatic stress due to the COVID-19 pandemic. Importantly, the pandemic is almost two years long already and the persistence of the stressor is associated with the chronicity of the disorder and with its comorbidity with psychiatric diagnosis ^[36]. Therefore, the population at risk of further psychiatric and psychological needs is high.

With regards to health care workers, systematic reviews and meta-analysis found that this professional sector had higher level of post-traumatic stress compared to general population: 13% [Krishnamoorthy, November, 2020], 11.4% ^[28] (December, 2020), 21.% ^[31] (March 2021) or two in every ten healthcare workers ^[37] (March 2021).

Finally, and for further research purposes, the instruments more employed to measure post-traumatic symptoms found in the meta-analysis and systematic reviews are, in alphabetical order: IES-R: Impact of Event Scale – Revised; PSS: Perceived Stress Scale; PTSD-SS: Self-Assessment Scale for Posttraumatic Stress Disorder; PTSS: Post Traumatic Stress Syndrome.

4. COVID-19 and Post-COVID-19 Psychological Symptoms

The COVID-19 infection may spread to the nervous system and cause cognitive impairment in patients, in consonance with reports about previous viral epidemics that found neurological disorders and cognitive alterations after infection ^[38]. These psychological consequences are not only restricted to the aforementioned disorders such as depression, anxiety and post-traumatic stress (meta-analysis show that infected patients reported anxiety, depression ^[39][40] and about three in every ten experienced PTSD symptoms ^[37]) but also expand to alterations in basic cognitive procedures.

Indeed, an analysis of more than 80 thousand participants supported the hypothesis that COVID-19 has a multi-domain impact on human cognition ^[41]. Importantly, a cohort study of almost 500 participants informed that negative cognitive performance appear to be associated to some COVID-19 symptoms: “headache, anosmia and dysgeusia constituted the main risk factors for cognitive impairment related with attention, memory and executive function [whereas] the need for oxygen therapy and diarrhea were also associated with memory, attention and executive function deficits” ^[42] (abstract). A systematic review found that studies reported cognitive deficits, fatigue at follow-up, and sleep disturbances, concluding that infected patients are “at risk of psychiatric sequelae but the symptoms generally improve over time” ^[39].

Unfortunately, the remission of symptoms from COVID-19 infection can also persist ^[41]. Following a Delphi methodology, namely, including patients, experts and physicians in the working team, the WHO has developed the definition for “post COVID-19 condition”: “Post COVID-19 condition occurs in individuals with a history of probable or confirmed SARS CoV-2 infection, usually 3 months from the onset of COVID-19 with symptoms and that last for at least 2 months and cannot be explained by an alternative diagnosis. Common symptoms include fatigue, shortness of breath, cognitive dysfunction but also others and generally have an impact on everyday functioning. Symptoms may be new onset following initial recovery from an acute COVID-19 episode or persist from the initial illness. Symptoms may also fluctuate or relapse over time.” ^[43].

A meta-analysis found the proportion of individuals experiencing fatigue 12 or more weeks following COVID-19 diagnosis was 0.32 (95% CI, 0.27, 0.37; p < 0.001; n = 25,268; I2=99.1%) whereas he proportion of individuals exhibiting cognitive impairment was 0.22 (95% CI, 0.17, 0.28; p < 0.001; n = 13,232; I2=98.0) 12 or more weeks following COVID-19 diagnosis ^[44] (December, 2021). The cognitive impairment included: ’brain fog’, mental slowness (i.e., increase in time needed to perform tasks such as reading/writing documents), deficits in attentional (i.e., difficulty in concentrating), executive, processing, memory (i.e., forgetfulness, spatial memory dysfunctions), learning (i.e., difficulties in learning new skills or procedures), articulation (i.e., difficulties to form words; feeling lost for words), and/or psychomotor coordination ^[40][44]. So far, the literature is scarce, and the heterogeneity of samples and procedures preclude generalization, however the recognition of the post COVID condition by WHO should encourage further investigation since the quality of life of the people affected may be reduced.

5. Conclusions and Prospects

The rapidness fluctuation and emergence of variants of the virus as well as the astonishing rhythm of publication of new COVID-19 related studies makes this entry easily out-of-date. However, there is some solid unperishable data:

1. Psychological impact associated with COVID-19 can be related to experiencing lockdowns; living in pandemic or getting infected.
2. COVID-19 lockdowns have not alarmingly and globally affected population, except for certain vulnerable subgroups and victims of crimes committed at home.
3. The absence of global alarming symptoms after lockdowns should not prevent for further vigilance after release, especially with regards to suicide.
4. Pandemic fatigue is a term coined to describe demotivation to follow preventive measures during prolonged public health crisis.
5. Living the COVID-19 pandemic has increased the rates of anxiety, depression and post-traumatic disorders in general population.
6. Certain subgroups are more at risk of suffering from anxiety (i.e., OCD patients) or depression (i.e., complicated grief).
7. The worst mental health burden is globally found in health care workers.
8. COVID-19 infection is associated with cognitive impairment and fatigue.
9. Post-COVID-19 condition is a term coined to describe the onset or persistence of fatigue, shortness of breath and cognitive dysfunction during 2 months, usually 3 months after having being infected.
10. The cognitive impairment of post-COVID-19 condition includes: ’brain fog’, mental slowness, deficits in attentional, executive, processing, memory, learning, articulation, and/or psychomotor coordination.