Predictors of severe COVID-19 among healthcare workers in Sabah, Malaysia

Since the pandemic of coronavirus disease 2019 (COVID-19) was declared by World Health Organization (WHO) on 11^th March 2020, the healthcare system has been severely impacted [1, 2]. All healthcare workers (HCWs) must work to face the pandemic, even during the national lockdown. These phenomena affect all HCWs, both physically and mentally. Various literature stated that the COVID-19 pandemic had been associated with psychological consequences for HCWs, including stress, depression, anxiety, trauma, burnout, and even suicidal attempts [1, 3‐5]. Another study showed that 36.5% of the HCWs working in UMMC experienced anxiety symptoms, while 29.5% reported depressive symptoms [4]. These harmful consequences of the pandemic on workers' mental health have prompted initiatives to prevent and control the problem through various mental health programs and religious coping [4, 5].

Besides being psychologically impacted, HCWs are also often considered a high-risk population for acquiring the infection as this population has frequent contact with COVID-19 patients and the risky working environment, such as treating patients in the indoor setting [6]. Despite becoming more resilient and improving occupational intervention to prevent infection among HCWs [7, 8], illness and death have profoundly affected the HCW. The previous report from the Italian health authority stated that 10.7% of overall COVID-19 cases were contributed by HCWs, with a rising number of deaths among medical doctors, nurses, nurse aides, and dentists [7]. In a large register-based cohort study among Scottish healthcare workers, HCWs and their households contributed to a sixth of COVID-19 cases [8]. A cohort study in the United Kingdom (UK) found that the essential workers, including HCWs, the risk of acquiring severe COVID-19 infection seven times greater compared to the non-essential workers (RR 7.43, 95% CI 5.52 to 10.00) [9]. Furthermore, the risk of disease among HCWs was more remarkable due to unprotected exposure to the infected individuals, involvement in aerosol-producing procedures, and contact with bodily secretions [10].

Severe COVID-19 infection can lead to long-term complications, including multisystem inflammatory syndrome, pulmonary fibrosis, and neurological manifestations [11‐16]. Even though there is greater awareness and strict adherence to infection control measures, HCWs had a higher risk of severe COVID-19 infection than other occupations and general populations [17, 18]. Hence, it is crucial to study the factors associated with severe COVID-19 disease in HCWs. Therefore, this article aims to describe the prevalence of severe COVID-19 infection among HCWs in Sabah, Malaysia, and to determine the factors associated with severe COVID-19 disease.

Three thousand forty (3040) healthcare workers (HCWs) were diagnosed with COVID-19 from 1^st March 2021 until 30^th September 2021. Of the 3040 HCWs, 2948 (97.0%) HCWs were mild, whereas 92 (3.0%) were severe (Table 1). About 2821 (92.8%) of the HCWs were vaccinated completely compared to incomplete vaccination (92, 3.0%) and not vaccinated at all (127, 4.2%), even though they were eligible. Among the positive HCWs, most were female (68.5%). HCWs with no co-morbidity contributed 2234 (73.5%) compared to those with co-morbidity, 806 (26.5%). Among the positive HCWs, nurses contributed the highest number, which is 1271 (41.8%), followed by medical assistants 527 (17.3%), doctors (256, 8.4%), inspectorate (146, 4.8%), dental (122, 4.0%), pharmacy (87, 2.9%) and other categories 631 (20.8%) such as administration, engineers, and laboratory personnel. Non-work related positive HCWs contributed 2383 (78.4%), and work-related were 657 (21.6%).

The dependent variable in this study is the staging of COVID-19 disease, which is mild and severe. There are seven independent variables: age, gender, staff categories, COVID-19 vaccination status, co-morbid, involvement in COVID-19 work, and source of infection. From the univariate logistic regression (Table 2), four variables are considered included in the multivariable logistic regression model using p-value < 0.25: age, gender, COVID-19 vaccination status, and co-morbidity.

After the four variables (age, gender, COVID-19 vaccination, and co-morbid) were included in the multivariable logistic regression model, only three variables were statistically significant (p-value ≤ 0.05), which is gender, COVID-19 vaccination and co-morbid (Table 3). The multivariable logistic regression model showed that severe COVID-19 among HCWs in Sabah was associated with those do not receive any COVID-19 vaccination (aOR 6.061, 95% CI 3.408 – 10.780), underlying co-morbidity (aOR 3.335, 95% CI 2.183 – 5.096), and female (aOR 1.833, 95% CI 1.090 – 3.081. The model has a satisfactory fit with a classification table of 97%.

Severe COVID-19 infection among healthcare workers (HCWs) in Sabah contributed to 92 cases from 3040 total COVID-19 diseases in this study which is 3.0%. The incidence of severe COVID-19 illness among the current study population is lower than in previous studies, with around 5% to 9.9% incidence of severe disease among HCWs, as reported in meta-analyses [20, 21]. The occurrence of severe infection in the current study is also lower than the reported severe infection among all COVID-19-positive patients. For example, a survey among hospitalized patients in France reported that 41% with severe diseases, including 32% requiring ICU admission and 11% deaths [22]. A similar finding also was documented in a study among patients admitted to a tertiary medical centre, where 74 (37.6%) patients required intubation [23]. The inconsistency of the prevalence is because HCWs might have better awareness regarding COVID-19 infection. Furthermore, greater access to testing facilities also enables the population to be identified earlier, allowing early treatment of the disease.

The current study identified several independent risk factors associated with severe COVID-19 infection among HCWs. The female gender is significantly associated with a greater risk of having severe COVID-19 disease than the male. However, the finding is inconsistent with previous studies that identified infected males as more likely to get severe COVID-19 infection than females [22, 24‐27]. Conflicting results in the current study might be explained by the imbalance in proportions of sex differences among all COVID-19 patients and among HCW. In the present study population, almost 70% of infected HCWs were female, most of whom were nursing staff. The more significant proportion of nursing staff in the current study might hinder the effect of the male gender on severe COVID-19 infection. Furthermore, the previous study also found the association of the male gender with severe COVID-19 illness is weak [25‐28]. In a physiological context, females have a higher copy number of immune-related genes, providing a more robust immune response, leading to high-stress endurance levels and better viral clearance. Consequently, lower mortality was observed [29].

Co-morbidity was also significantly associated with severe COVID-19 infection among HCWs. The current study found that HCWs with co-morbidity have a three times greater risk of acquiring severe COVID-19 infection than those without co-morbidity. Previous studies reported that co-morbidity such as immunosuppression [22, 30], diabetes [22, 25, 27, 28, 30, 31], hypertension [26, 28], acute or chronic kidney disease [22, 23], chronic obstructive pulmonary disease [31], bronchial asthma [25, 30], and gastrointestinal condition [27, 28, 30] were associated with severe COVID-19 infection and death. Furthermore, the previous study also similarly found that patients with haematological co-morbidities such as acute myeloid leukaemia (3·49, 1·56–7·81), indolent non-Hodgkin lymphoma (2·19, 1·07–4·48), aggressive non-Hodgkin lymphoma (2·56, 1·34–4·89), and plasma cell neoplasms were associated with worse COVID-19 survival [32]. Previous meta-analyses found that severity is most remarkable in patients with a history of cerebrovascular disease: OR 4.85 (95% CI: 3.11–7.57), cardiovascular disease: OR 4.81 (95% CI: 3.43–6.74), chronic lung disease: OR 4.19 (95% CI: 2.84–6.19), and cancer: OR 3.18, 95% CI: 2.09–4.82 [33]. The high prevalence of co-morbidity among infected HCWs in our study requires urgent intervention to protect the affected HCWs from serious sequelae of COVID-19 infection, including long COVID-19 syndrome, acute respiratory distress syndrome (ARDS), multi-organ failure, septic shock, and death [34, 35].

Vaccination is one of the essential public health interventions to prevent severe COVID-19 infection. The current study found that HCWs who are unvaccinated or had incomplete vaccination history are more likely to have severe COVID-19 disease by two to six times respectively, than those who had completed COVID-19 vaccination. The finding is supported by a previous study that found that receiving at least two doses of vaccination reduces the risk of hospital admission by 93%, 92% for severe COVID-19, and 81% for COVID-19-related deaths [36]. This finding further underscores the importance of vaccination among HCWs and those with co-morbidities [37]. A recent study also highlights the importance of third-dose mRNA vaccination in protecting individuals against severe COVID-19-related outcomes [36].

Previous studies among the general population have found that advancing age, especially greater than 60 years old, was an independent risk factor for severe COVID-19 infection and deaths [22, 25‐27]. The elderly population is at high risk for severe COVID-19 disease because they have weakened immunity and viral-induced cytokine storms, resulting in life-threatening respiratory failure and multisystemic involvement [38]. Since HCWs are among productive age groups, the age factor was not significantly associated with severe COVID-19 infection in the current study. In the present study, even though the age factor is not a significant concern, these populations must be regularly screened for co-morbidity, especially before retirement, to protect them when they enter high-risk age groups. The current study also found that the various HCW professions and probable sources of infection were not significantly associated with severe COVID-19 disease. However, in past literature, it was observed that HCWs working at the front door, intensive care unit and aerosol-generating procedure settings were associated with hospital admission [8]. The inconsistency of findings with the current study might be because the present study did not stratify the staff's background, as some HCWs might not work directly with COVID-19 patients. Furthermore, the current study also identified that most of the infection originated from non-work-related conditions.

From the study, there are several recommendations. Assessing awareness and practice regarding preventive measures against COVID-19 might help determine the need for tailored health education programs among HCWs to improve the appropriate method of COVID-19 prevention practices [39]. With the advancement of technology and computer science, the current surveillance system for early detection of COVID-19 infection among HCWs could be improved through disruptive technology such as the Internet of things, artificial intelligence, and blockchain [40]. Previous research has reported that ventilation is essential in transmitting infectious diseases, such as severe acute respiratory syndrome and influenza [41]. Therefore, a future study in assessing indoor air quality in healthcare settings might be needed to determine the potential neglected source of infection with subsequent intervention to improve ventilation. For HCWs, strict adherence to preventive measures, including vaccination, early and self-referral to the physician upon identification of severe COVID-19 infection may help to prevent further progression and complications of COVID-19. For public health practitioners, early screening and treatment of co-morbidity are of utmost importance for preventing severe COVID-19 infection among HCWs. HCWs with uncontrolled co-morbidities are the group to be prioritized to get the vaccination. Occupational health policy emphasizing the protection of HCWs from COVID-19 infection should be prioritized in public and private healthcare facilities.

This study is not without limitations. A cross-sectional study design where the data was collected at a single time point and the association between predictors and outcome may not be taken as an indication of causality, and reverse causality is possible. Furthermore, because of the retrospective nature of this study, some of the critical variables, especially potential confounders such as the laboratory, inflammatory, infection markers, and behavioural risk factors, were unavailable. In addition, a possible lack of detailed clinical data and self-reporting of co-morbidity could limit our findings. Thus, some variables' role in predicting severe COVID-19 infection could have been underestimated. Nonetheless, the heterogenicity of our study population, involving all healthcare staff regardless of whether they work in clinical or non-clinical practice, provides valuable information on potential predictors of severe disease in the population.

In conclusion, the study has elucidated the list of vulnerable populations among HCWs that predicted severe COVID-9 infection, including gender, vaccination status, and co-morbidity. The findings from our study have several implications for various stakeholders, such as HCWs, public health practitioners, policymakers, physicians at healthcare facilities, and intensive care physicians. Regardless of the co-morbidity status, the HCW are recommended to stay up to date with their COVID-19 vaccination, including booster doses. Strict adherence to preventive measures and occupational health policy is of the utmost importance to prevent severe COVID-19 infection among HCWs.