The search of the electronic literature yielded 1055 unique citations. Ten citations were found through other sources. After removing the duplicates, 691 articles were assessed through the title and abstract and 621 were excluded. After reviewing the full texts, 36 articles were included in the review (see Fig. 1 in ESM2).
The key characteristics of the included studies are presented in Table 1. An exhaustive description of the studies’ main findings is reported in ESM3.
The 36 included studies were conducted in ten different countries, mainly Taiwan (N = 8, 22.2%), Republic of Singapore (N = 7, 19.4%), and Canada and China (N = 6, 16.7%). The vast majority of the studies had a cross-sectional design (N = 29, 80.5%) and were published between 2004 and 2020. Six studies had a qualitative design and one a prospective design. Self-reported questionnaires were used in all the cross-sectional studies. Most of the research studies were conducted during or soon after the pandemic (N = 23, 64%). More than half of the studies (n = 25, 69.4%) regarded the 2003 SARS epidemic. Four studies were conducted during or immediately after the N1H1 outbreak, five studies after the MERS outbreak and two studies during the COVID-19 pandemic.
Study participants and settings
The quantitative studies assessed a total of 13,711 participants. The number of respondents ranged between 26 and 1625. The qualitative studies involved a total of 246 participants, ranging from seven to 188. In most studies, female respondents were over-represented. The most represented clinical setting was the general teaching hospital (15 studies, 41.7%), followed by tertiary care hospitals (six studies, 16.7%). Nurses and physicians were the two types of HCWs mostly involved, with 28 (77.8%) and 23 (63.9%) studies, respectively, followed by healthcare assistants (HCAs). In 11 studies, the profession of the participant was not reported (see ESM4).
In cross-sectional studies, the response rate, when reported, varied between 27 and 96.9%. Cross-sectional studies usually examined the prevalence and correlates of epidemic-related psychosocial outcomes in several different HCW groups.
Measurement of psychosocial outcomes
Of the 36 studies, 20 adopted validated measures of psychosocial outcomes (Table 2). Five studies measured work-related stress and burnout, 16 measured post-traumatic stress disorder symptoms and 15 measured psychological well-being. Of the burnout studies, the majority used some variants of the Maslach Burnout Inventory (Maunder et al. 2006; Austria-Corrales et al. 2011). Post-traumatic stress disorder symptoms were mostly assessed (Chan and Chan 2004; Verma et al. 2004; Chong et al. 2004; Maunder et al. 2004, 2006; Sin and Huak 2004; Tham et al. 2005; Chen et al. 2005a, b; Phua et al. 2005; Styra et al. 2008; Wu et al. 2009; Matsuishi et al. 2012; Bukhari et al. 2016; Tan et al. 2020) with the Impact of Event Scale or some of its variants. The psychological well-being measures—adopted in 15 studies—were far more varied and in most of the studies included: the General Health Questionnaire (GHQ)—or a variant of it—which was used in seven studies (Chan and Chan 2004; Sin and Huak 2004; Tam et al. 2004; Verma et al. 2004; Phua et al. 2005; Tham et al. 2005; Goulia et al. 2010) or the Chinese Health Questionnaire, which was used in 3 studies.(Chong et al. 2004; Lu et al. 2006; Lung et al. 2009) Finally, mood symptoms were assessed though a wide range of instruments such as the Beck Depression Inventory, the 9-item Patient Health Questionnaire, the 7-item Generalized Anxiety Disorder and the 7-item Insomnia Severity Index. Table 2 shows in more detail the specific instruments adopted by each study to measure the HCWs’ psychosocial outcomes related to the management of the epidemic. Few studies analysed psychological stress in non-clinical healthcare workers, such as administrative staff, clerical staff, logistic and maintenance staff. Although this staff is not directly involved in the care of patients, their work is of vital importance to sustain those in the front line. A study (Tan et al. 2020) reported that this staff had an even higher psychological distress than HCWs.
Impact findings about the psychosocial response to pandemics
Across all the studies—both qualitative and quantitative—HCWs working during the epidemic reported frequent concerns regarding their own health and the fear of infecting their families, friends and colleagues. They frequently suffered social isolation (Maunder et al. 2003, 2004, 2006), uncertainty (Chong et al. 2004) and fears of stigmatization (Bai et al. 2004; Verma et al. 2004), reluctance to work or considering absenteeism (Bai et al. 2004). Moreover, many studies highlighted a high prevalence of high levels of stress, anxiety and depression symptoms, which could have long-term psychological implications in HCWs (Maunder et al. 2003; Chong et al. 2004; Chen et al. 2005a; Grace et al. 2005; Su et al. 2007; Matsuishi et al. 2012; Lai et al. 2020). Stigmatization was a frequent theme emerging also in qualitative studies (Maunder et al. 2003; Almutairi et al. 2018).
Factors associated with the psychosocial response to pandemics
Four main categories of variables related to psychosocial outcomes were identified: (1) sociodemographics; (2) psychological characteristics; (3) professional attitudes and characteristics; and (4) organizational environment. Finally, two contextual elements appeared relevant in shaping the psychological reactions of HCWs: being quarantined and the epidemiological phase of the disease outbreak.
Among the sociodemographic factors, age (Wu et al. 2009), sex (Chong et al. 2004; Lai et al. 2020), marital status (Chen et al. 2005a, b) and educational level (Chua et al. 2004) showed some associations with epidemic-related psychosocial outcomes on HCWs, although circumstantial.
Several studies reported the relationship between HCWs’ psychosocial outcomes and organizational aspects, such as working in high-risk locations (Chua et al. 2004; Chen et al. 2005a; Styra et al. 2008), lack of clear communication from organizations (Chan and Chan 2004), lack of support from colleagues (Chan and Chan 2004), specific clinical procedures (i.e. emergency resuscitation) (Chen et al. 2005b), unprotected exposure to infected patients (Lu et al. 2006; Styra et al. 2008) and inadequate organizational support (i.e. counselling and psychological support from the employer, and insurance and compensation)(Khalid et al. 2016).
Some studies reported the relationship between psychosocial distress and professional characteristics, such as job titles (Chen et al. 2005a), work satisfaction (Tolomiczenko et al. 2005), job-related stress (Maunder et al. 2004), technical titles (i.e. junior, intermediate, senior) (Chen et al. 2005a, b; Khalid et al. 2016) and not feeling sufficiently trained in infection management (Wong et al. 2005).
Some studies focused on the relationship between psychosocial distress and individual psychological resources or characteristics, such as maladapting coping style (Chan and Chan 2004; Maunder et al. 2006; Oh et al. 2017), social isolation (Maunder et al. 2004; Goulia et al. 2010), perceived risk of self-infection (Khalid et al. 2016), previous history of mood disorders (Su et al. 2007), personality traits (Lu et al. 2006) and attachment style (Lu et al. 2006; Lung et al. 2009).
Finally, across the factors associated with the psychosocial outcomes, the specific phase of the epidemic course has been shown to be associated with symptom exacerbation (Wu et al. 2009).
A wide range of intervention strategies to reduce emotional distress in HCWs exposed to the epidemic outbreaks emerged from the included studies, which can be classified in policy, organizational and person-directed strategies (see ESM5 for a detailed synthesis).
At the policy level, nine studies suggested to develop a strategic plan for future outbreaks (Sin and Huak 2004; Tolomiczenko et al. 2005; Wong et al. 2005; Lu et al. 2006; Maunder et al. 2006; Holroyd and McNaught 2008; Lung et al. 2009; Corley et al. 2010; Kim 2018) and one study to conduct public campaigns to protect HCWs and reduce their stigmatization (Matsuishi et al. 2012). From an organizational point of view, many studies underlined how it is important to ensure favourable work conditions (Bai et al. 2004; Maunder et al. 2006; Su et al. 2007; Austria-Corrales et al. 2011; Matsuishi et al. 2012) and provide HCWs with all the personal protective equipment (PPE) necessary to work safely and reduce their risk (Chen et al. 2005a, b; Goulia et al. 2010; Khalid et al. 2016). Organizations should also promote HCWs personal coping strategies, such as altruism, acceptance, resilience and humour (Lee et al. 2005; Wong et al. 2005; Wu et al. 2009).
The majority of the included studies underlined the importance of psychological support before, during and after the outbreak, provided by specially trained personnel (Bai et al. 2004; Tam et al. 2004; Verma et al. 2004; Chan and Chan 2004; Chong et al. 2004; Khee et al. 2004; Lee et al. 2005; Phua et al. 2005; Tham et al. 2005; Wong et al. 2005; Chen et al. 2005a, b; Grace et al. 2005; Su et al. 2007; Styra et al. 2008; Wu et al. 2009; Corley et al. 2010; Matsuishi et al. 2012; Almutairi et al. 2018; Kim 2018; Lai et al. 2020; Tan et al. 2020). It is important also to provide social support for HCWs’ families (Grace et al. 2005; Bukhari et al. 2016) and recognize HCWs’ efforts by providing positive feedback (Maunder et al. 2006; Khalid et al. 2016). Included studies highlighted also how physical well-being is important to maintain psychological stability (Maunder et al. 2003; Bai et al. 2004; Goulia et al. 2010). A collaborative climate within the clinical team is also important to promote social support, and reduce conflict and the negative effects of social isolation (Maunder et al. 2003, 2004, 2006; Khee et al. 2004; Lee et al. 2005). Furthermore, studies—both qualitative and quantitative—stressed the centrality of providing HCWs with accurate and timely information to reduce uncertainty (Maunder et al. 2003, 2004, 2006; Bai et al. 2004; Sin and Huak 2004; Corley et al. 2010; Goulia et al. 2010; Matsuishi et al. 2012; Khalid et al. 2016) as well as training and education about how to protect themselves and properly deal with infected patients (Maunder et al. 2003, 2004, 2006; Bai et al. 2004; Sin and Huak 2004; Chua et al. 2004; Chen et al. 2005a, b; Corley et al. 2010; Bukhari et al. 2016; Oh et al. 2017).