Background

The novel coronavirus pneumonia has spread globally since 2020 [1], resulting in almost 701 million infections and approximately 6.9 million deaths by early 2024 [2]. The coronavirus disease 2019 (COVID-19) pandemic has significant detrimental effects on the global economy [3], physical health (severe acute syndrome [4] and sequelae [5]), as well as people’s daily lives [6, 7]. The waves of COVID-19 pandemic marked by the emergence of new variants and vaccination, e.g., the outbreak of the Omicron variant and Delta variant [17]. It indicates that psychological distress and associated factors may vary at different stages of the peri-infection period. Previous studies focus on the psychological distress either among general population or among patients with Long COVID-19 [5, 13,24].

Risk perception and intolerance of uncertainty (IU), two major factors involving in disease-associated psychological distress, may contribute to the effect of residual symptoms on psychological distress [25,26,27]. Risk perception of COVID-19 refers to an individual’s cognitive response, assessment, experience, and subjective feelings toward the risk associated with COVID-19 [28]. Residual symptoms following acute COVID-19 syndrome may indicate a prolonged negative impact on health [29], potentially leading to an increased perception of severity and persistence of COVID-19. The elevated levels of risk perception and appraisal may link to increased psychological distress [30]. Moreover, IU is a personal psychological trait that reflects a person’s inability to endure aversive responses, leading to negative reactions toward unpredictable situations or uncertain events, regardless of the probability of occurrence [31, 32]. For example, IU was a significant predictor of psychological distress during the COVID-19 pandemic [33]. It suggests that IU may potentially influence the connection between risk perception and psychological distress.

This study aimed to examine the psychological distress of individuals during the COVID-19 infection process, from high risk to contact the virus to infected within 1 month. Moreover, the effect of residual symptoms on psychological distress was examined, which fills the research gap between acute phase of COVID-19 and Long COVID. Furthermore, the moderated mediating effect of risk perception and IU on the relationship between residual symptoms and psychological distress was explored. Three hypotheses were proposed to achieve these objectives: (1) The level of psychological distress varies among individuals at different stages of COVID-19 infection; (2) Individuals with residual symptoms are more likely to experience more severe psychological distress; (3) The relationship between residual symptoms and psychological distress is mediated by risk perception and moderated by IU.

Methods

Study design and recruitment

This was a cross-sectional, descriptive and correlational study. Participants were categorized into different stages based on COVID-19 infection status, ranging from never being infected to fully recovery. The survey was conducted from January 12 to January 21, 2023. Most patients have recovered from acute phase of COVID-19 infection within this time window [34].

Convenience sampling was utilized in this study due to the unique nature of emergencies. Online recruitment was conducted in the form of Quick Response (QR) code through electronic questionnaires powered by “Questionnaire Star” (https://www.wjx.cn/). Participants were recruited using social media: WeChat and WeChat Moments. All participants were presented with study-related information and asked about consent preferences. The Ethics Committee of The Affiliated Kangning Hospital of Wenzhou Medical University approved this study (Approval Code: YJ-2023-16-01) following the Helsinki Declaration.

Participants

A total of 1800 individuals completed the questionnaires. The questionnaires were individually checked by two investigators to eliminate those with extremely short filling times (less than 200s) or obvious random filling. Individuals who had been infected with COVID-19 for more than one month were excluded. 1735 completed questionnaires were included in the study. The exclusion rate was 3.61%.

Measurements

Demographic factors and COVID-19-related information

Demographic factors were collected, including age, gender, religiosity, family financial situation, and physical health. COVID-19-related information was collected, including COVID-19 vaccination status, medicines preparation, financial losses during the pandemic and after lifting the COVID-19 policy, infection of relatives and friends, individual’s infection status and time of infection, recovery status, and any residual symptoms experienced after acute remission and nucleic acid turned negative.

Proposed stages of COVID-19 infection

The whole COVID-19 infection process was categorized into three stages based on the individual’s infection status (Supplementary Figure S1). The infection status was determined by asking, “Have you ever been infected with COVID-19?”, with three possible responses: (1) never, and do not exhibit any symptoms related to the virus such as fever, sore throat, cough, etc.; (2) never, but display suspicious symptoms related to the virus; and (3) have been infected with COVID-19 confirmed by a nucleic acid or antigen test. Participants who answered (1), (2), and (3) were categorized as stage 1, 2, and 3 groups, respectively. For participants who answered (3), an additional question “When were you first infected with COVID-19?” was asked. The response options were (1) within 1 week, (2) from 1 week to 1 month, and (3) over 1 month. Participants with answer (1) and (2) were clustered into ‘acute phase’ (stage 3a) and ‘chronic phase’ (stage 3c) of stage 3, respectively (Supplementary Figure S1). Participants with answer (3) were excluded from the current study.

Residual symptoms

COVID-19 related symptoms during the acute remission (within 1 month) were defined as residual symptoms, which differentiate from Long COVID (over 1 month). Residual symptoms should satisfy three criteria: (1) Individuals have been diagnosed with COVID-19 by nucleic acid or antigen detection; (2) Individuals have recovered from the acute syndrome and nucleic acid or antigen detection is negative; (3) COVID-19-related symptoms are still present within one month of infection.

To measure residual symptoms among participants who answered “have been recovered from COVID-19 acute syndrome and nucleus acid or antigen tests were negative”, the item ‘Do you still have symptoms (i.e., fever, cough, sore throat, stuffy nose, and fatigue)?’ was asked. Participants who answered ‘yes’ were categorized into the group with residual symptoms.

Risk perception of COVID-19

The COVID-19 Risk Perception Scale, developed by Cui ** with insecurity and uncertainty during COVID-19 infection. Therefore, high IU may amplify the effect of risk perception on depressive and anxiety symptoms, contributing to psychological distress. In contrast, the effect of risk perception on depression and anxiety tended to be non-significant in the participants with low IU, which indicated that IU plays a key role in the emergence of psychological distress in COVID-19 survivors. Previous studies have also found that IU was directly associated with higher depression and anxiety [25, 26], which is consistent with our study. Therefore, intervention in risk perception and IU may alleviate psychological distress. For instance, cognitive-behavioral therapy (CBT) might be helpful to affect one’s perceived risk and uncertainty [62].

Despite the moderated effects found in models of depression and anxiety, a distinct pattern emerged in the associations with fear of COVID-19. The mediating effect of risk perception appeared to play a major role in the association between residual symptoms and fear of COVID-19, while the moderating effect of IU was not evident. The positive association between risk perception and fear of COVID-19 aligns with previous findings [63, 64]. High risk perception and compromised health status have been reported to be robust contributors to heightened fear of COVID-19 [65]. A decline in physical health status may alter the perception of the COVID-19 risk, consequently contributing to higher levels of fear of the disease. Fear is typically an emotion directing towards a specific object, serving to motivate people to avoid potential danger. In contrast to the effects in depression and anxiety models, IU did not modulate the relationship between risk perception and fear of COVID-19. This disparity suggests that the fear of COVID-19 may directly stem from specific and definite negative consequences of COVID-19, such as residual symptoms and distressing experiences.

Compared with manifestations of COVID-19 in its presymptomatic and prodromal periods, the emergence of post-COVID syndrome has become a more prevalent public health concern in the current period. As some residual symptoms may be persisted and evolve into post-COVID syndrome, there is a critical transition phase between the acute phase and post-COVID syndrome. Individuals in this transition phase may be especially at risk of psychological distress, as they experience more severe physical symptoms than post-COVID syndrome and worry about the risk of transforming to post-COVID syndrome. Since the psychological distress has been identified as a risk factor of post-COVID syndrome [66, 67], our research sheds light on the potential mediator and moderator in the relationship between residual symptoms and psychological distress. As discussed above, these psychological factors (i.e., risk perception and IU) have been identified as potential targets for psychological intervention, offering the possibility to mitigate psychological distress and the risk of post-COVID syndrome. Therefore, this study holds significant implications for co** with this critical transition phase, thereby addressing a notable gap in the existing body of COVID-19 research.

To the best of our knowledge, this study is the first to investigate the possible psychological differences from never infected with COVID-19 stage to the chronic phase of COVID-19, and to explore the effects of residual symptoms on psychological distress and underlying mechanism. Our study identifies the significant impact of residual symptoms on psychological distress and the key role of risk perception and uncertainty intolerance (IU). It indicated that two psychological structures can be intervened in. However, the present study has several limitations. First, the generalizability of the study’s findings may be constrained by the use of convenience sampling and the limited number of elderly participants. As such, caution is warranted when extending the conclusions beyond the sampled population. Second, the limited number of participants within a week after COVID-19 infection should be considered when interpreting the subgroup analysis results. Third, this study follows a cross-sectional design, which necessitates longitudinal cohort studies to confirm the causality and long-term dynamics of residual symptoms.

Conclusion

A considerable proportion of patients experience residual symptoms after the acute phase of COVID-19, which have a significant impact on psychological distress. Risk perception and intolerance of uncertainty play a moderated-mediation role in the association between residual symptoms and depression/anxiety. It highly suggests that effective treatment for residual symptoms, maintaining appropriate risk perception and improving intolerance of uncertainty are critical strategies to alleviate COVID-19 infection-associated psychological distress.