Discussion

The COVID-19 pandemic highlighted the necessity of health agencies worldwide to be well prepared to combat large-scale emerging infectious diseases. In the context of the outbreak of a novel severe respiratory infectious disease, especially at the early stage, reliable information of the pathogenic etiology and mechanism, mode of transmission, clinical presentation characteristics, and susceptible populations is lacking – and the availability of effective vaccines can be months to years away. To prevent cross-infection in hospitals, which may represent major spreading events of the infection and a significant impact to the occupational safety of HCWs, a standard and effective protocol of occupational protection is essential. Protective clothing, masks, and other PPE for HCWs entering wards to manage patients are already well accepted in the infectious disease units. In China, the dates when the peak of COVID-19 occurred were particularly unusual. It was during the traditional Spring Festival when manufacturing work was suspended almost all over China; thus, there was a marked shortage of production and supply of the PPEs. The vital role of medical care in the event of a huge number of patients, the fear of the unknown due to lack of sufficient information on the disease itself, and the pressure of public opinion place HCWs under huge psychological pressure. We experienced a stage when ORAEs, such as nausea/vomiting, headache/dizziness, tenderness, palpitation, dyspnea, and blurred vision, frequently occur in contaminated areas, and the incidence of occupational exposure, such as respiratory exposure, syncope, and needle stick injuries, was also relatively high, causing great physical and psychological burdens on HCWs. ^{Reference Tang, Lu and Cai5}

This study found that a long duration use of PPEs was the most important cause of ORAEs, which might be related to generally high-level protection while the effectiveness and necessity were not clearly defined. Although it is clearly not advisable to lower the protection level when the transmission mode of a novel severe respiratory infectious disease is unclear, optimizing the procedures of PPEs should be one of the key research areas to improve occupational safety for HCWs and enhance the quality of medical care, so that we can be more prepared for the emerging infectious diseases in the future. There are several key components of PPEs, and each may be improved to alleviate the risk of ORAEs. The protective clothing usually becomes sultry easily. Improving the air permeability of protective clothing material could be a practical way to reduce the burden of long-duration work while wearing these gowns. In practice, Tyvek medical protective clothing has excellent air permeability, with effective protectiveness, and has been highly approved for frontline HCWs. ^{Reference Lu and Zhang6} Mask suffocation is a major factor of ORAES. We think the following measures can be considered to reduce AEs: First, reducing the respiratory resistance by better manufacturing; second, decreasing the work duration and intensity by increasing the number of HCWs per shift would certainly improve the subjective feeling of mask suffocation; third, as irritating smells of masks can aggregate the perception of ORAEs, increasing the purity of the materials and improving the manufacturing process may help reduce some uncomfortable smells of masks. Many studies have reported that pressure injuries on skin associated with medical devices are caused by tightly worn goggles and masks. These injuries not only cause skin damage and pain, but also increase the risk of skin infection. We found that the use of protective dressing can reduce local friction, help absorb exudation, and promote repair while still ensuring that the airtightness of the mask and goggles are adjusted properly. If any pressure injuries are found, they should be properly treated. Antifogging agents applied to goggles are the most common way to prevent blurred vision. Although many goggles and protective face screens have antifogging features, moisture-resistant coatings are frequently destroyed by disinfectants. Povidone-iodine or detergents, such as handwashing solutions, may be reasonable substitutes when antifogging agents are in shortage. Anionic surfactants in detergents can reduce surface tension effectively to achieve moisture resistance; molecular iodine formed after povidone-iodine oxidation may also achieve moisture protection. Those alternative methods can generally achieve more than 2-hour antifogging effects, reducing the occurrence of ORAEs caused by blurred vision. ^{Reference Li and Cao7} Last, but not least, overuse and misuse of PPE should also be discouraged. Overuse of PPE by overlapping/double protective clothes, goggles, and masks results in a significant waste of already limited medical resources and increased disposal burden. Among non-PPE-related factors, HCWs were found to have a higher prevalence of insomnia, and it was also associated with most ORAEs in contaminated areas. Similar results have been reported in previous studies. ^{Reference Nicolle8–10} When providing diagnoses and treatments to critically ill patients, due to frequent overtime work with higher intensity and occupational safety risk, HCWs would inevitably break sleep habits, which then lead to disruption of the biological clock. Long-term and persistent stressful events not only increase the risk of newly onset insomnia, but also enhance chronic insomnia. To mitigate the burden of insomnia for this group of people, the prevailing protocol is to deploy professional psychotherapists with active individual intervention, supplemented by the use of sedative hypnotic medicines. On the other hand, Car sickness is a risk factor that arises in a particular background. During the COVID-19 outbreak in Wuhan, HCWs were gathered in dormitories located more than 40 kilometers from the hospital and commuted with specially assigned shuttle buses so as to facilitate workforce management and to avoid cross-infection. As a result, multiple cases of ORAEs in contaminated areas associated with car sickness had been observed. Therefore, measures to reduce car sickness, such as reducing commute time by moving to closer lodging, training drivers to avoid operations that might induce car sickness, and distributing prophylactic pills to HCWs vulnerable to car sickness, may decrease the risk of ORAEs. Additionally, working duration in the contaminated “red zone” was also a crucial risk factor. The increased risk was associated not only with the clinical workload, but also the lengthy procedure to take off PPEs. There are potential risks of infection with several HCWS undressing PPE simultaneously within a limited space. Actually, there had been reports of infection events due to inappropriate PPE undressing every now and then. ^{11 , 12} Therefore, HCWs had to undress PPEs sequentially following a strict protocol, which became a factor contributing to extended work time in contaminated areas. The problem became serious when numerous HCWs were required to enter the contaminated area at the same time as a large number of patients were admitted. Additional ameliorating measures to reduce risk of ORAEs for non-PPE related factors include setting up reasonable shift arrangement and increasing the number of HCWs per shift to alleviate fatigue and insomnia. In our experience, screening of AEs (eg, car sickness, insomnia) before entering contaminated areas, and appropriate intervention, when necessary, helped effectively reduce the negative impact of non-PPE-related factors. Needless to say, sufficient instructions and training on PPE on/off protocols are critical to ensure that HCWs are cultivating a good routine habit. One of the main reasons for occupational exposure at the early stage of the COVID-19 outbreak was insufficient protection for HCWs due to lack of PPE stocks and poorly implemented infection control measures. A study has confirmed that sufficient PPE could effectively decrease the occupational exposure of HCWs. ^{Reference Chen, Wei and Wang13} Even if given sufficient supplies and assuming all being used adequately and reasonably, it’s still extremely important to ensure a thorough implementation of infection control measures, especially when many HCWs without much experience in dealing with infectious disease join the special workforce to combat the pandemic. For instance, by conveying the knowledge, improving the perception and behavior, strengthening the notion that “behavioral isolation” is superior to “physical isolation,” it is effective to maximize the contribution of PPEs in our experience.

One advantage of our bundled intervention model is the ability to make all aspects of the infection and AE risk controllable. Professional measures of infection control can not only decrease the infection rate, ^{Reference Correa-Martínez, Schwierzeck and Mellmann14} but also increase HCWs’ confidence to work against the viral infection. At the early stage of the pandemic, concerns and fears related to COVID-19 were prevalent among HCWs. ^{Reference Shreffler, Petrey and Huecker15} So far, a majority of interventional research studies have assessed occupational exposure based on the SHEL model ^{Reference Guo, Lu and Wang16,Reference Molloy and O’Boyle17} and the Reason model ^{Reference Reason18} ; these methods analyzed occupational exposure caused by mismatchs between individual factors and the corresponding microenvironment from the perspective of system theory. The bundled interventions of this study were based on the findings of early investigations and then focused on taking actions against the most relevant issues. The bundled interventions had been effective, as indicated by the results of this study. Through these interventions, many HCWs became more compliant with the protection procedures; some incorrect perceptions, such as the notion that more and thicker PPEs offer better protection, were scientifically addressed. The results of our investigation and implementation in clinical practice indicate that this intervention model has high effectiveness and feasibility.