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Contamination of personal protective equipment and environmental surfaces in Fangcang shelter hospitals

Published:November 23, 2022DOI:https://doi.org/10.1016/j.ajic.2022.11.016

      Highlights

      • Fangcang shelter hospital HCWs are under risk of hospital infection
      • SARS-CoV-2 contamination is extensive on PPE and environmental surfaces
      • Viral RNA positivity is most extensive in patient occupied areas
      • Potentially contaminated areas and surfaces after cleaning are all negative

      Abstract

      Background

      Fangcang shelter hospitals emerged as a new public health concept after COVID-19. Data regarding contamination of Fangcang shelter environments remains scarce. This study aims to investigate the extent of SARS-CoV-2 contamination on personal protective equipment and surfaces in Fangcang hospitals.

      Methods

      Between March and May 2022, during wave of omicron variant, a prospective study was conducted in two Fangcang hospitals in Shanghai, China. Swabs of personal protective equipment worn and environmental surfaces of contaminated areas, doffing rooms, and potentially contaminated areas were collected. SARS-CoV-2 RNA was detected by reverse transcription quantitative polymerase chain reaction. If viral RNA was detected, sampling was repeated after cleaning and disinfection.

      Results

      A total of 602 samples were collected. 13.3% of the personal protective equipment were contaminated. Positive rate was higher in the contaminated areas (48.4%) than in the doffing rooms (11.7%) and the potentially contaminated areas (0; P<0.05). Contamination was highest in patient occupied areas 67.5%. After cleaning, samples taken at previously contaminated surfaces are all negative.

      Conclusions

      SARS-CoV-2 RNA contamination is prevalent in Fangcang hospitals and healthcare workers are under risk of infection. Potentially contaminated areas and surfaces after cleaning and disinfection are negative, underlying the importance of infection control policy.

      Key words

      Abbreviations:

      COVID-19 (coronavirus disease 2019), SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2/ novel coronavirus), PPE (personal protective equipment), HCW (healthcare worker), DR (doffing room)

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      . However, researches were conducted mostly in acute care hospitals and designated wards for COVID-19 patients. Data regarding Fangcang shelter hospitals remains scarce. In order to fill this gap, this current cross-sectional study prospectively investigated the SAR-CoV-2 contamination of PPE worn by staff and various environmental surfaces of two Fangcang hospitals in Shanghai, China. We present the following article in accordance with the STROBE reporting checklist.

      Material and Methods

      Research design

      Between March and May 2022, during the Omicron wave of the pandemic, a prospective, observational, cross-sectional study was conducted in two Fangcang shelter hospitals in Shanghai, China. The hospitals were converted from an empty campus site and an art exhibition center, which could contain a maximum of 500 and 1500 patients, respectively. Audio and video monitoring of the donning and doffing rooms were routinely practiced. During the study period, HCWs worked and lived “closed looped” according to policy with minimal cross infection possibility. The “closed looped” strategies are administrative measures bundles adopted in higher risk settings. For Fangcang hospitals, they included: Only specified personnel are allowed to enter designated areas. During their service period, HCWs are under medical observations. Staff mobility is restricted and recorded.
      Sampling of PPE, skin, and environmental surfaces of various areas were taken by swabs after shifts/ ward rounds. Healthcare workers included staff members who worked shifts inside contaminated areas of Fangcang hospitals. Their identity and time spent inside were recorded. Surfaces sampled included patient occupied areas, public areas inside the contaminated areas, doffing rooms, and potentially contaminated office and living areas. Sampling of environmental surfaces took place about 5hours after the previous round of cleaning/disinfection.
      One swab covering 100cm2 surface area was taken for each sample site, or adjusted according to shape. Each swab was contained in one sampling tube. After the initial sampling and PCR tests, swabs of contaminated surfaces were recollected for testing after routine cleaning and disinfection. Only results of the first samplings were counted in the calculation of contamination rates.

      Sampling objects

      PPE and skin surfaces

      Two individuals from each work group, including administrations, clinicians, nurses, cleaners, and securities that worked shifts inside the contaminated areas were investigated. Eleven samples from various PPE surfaces and 1 sample of human skin surface were taken from each person. At the entrance of the first doffing rooms (DR1), swabs of face shield, bilateral coverall sleeves, coverall chest area, coverall cap (head and neck), outer layer of gloves, and outer shoe covers were taken. In the second doffing rooms (DR2), swabs of N-95 respirators, inner gloves, inner shoe covers, scrub suit tops, scrub suit trousers, and skin of face, neck and hands of the workers were taken.

      Environmental surfaces

      Contaminated areas: Samples of frequently touched objects including bedside tables, bed rails, beddings, chairs, and floors were taken in patient occupied areas. In public areas, nurse station desks, nurse station computers, hospital admission desks, water dispensers, waste bins, and toilets were sampled. Doffing rooms: Door handles, desktops, walls, mirrors, waste bins, and floors of the first and second doffing rooms were sampled respectively. Potentially contaminated areas: Frequently touched surfaces of the HCW's office and living areas outside the contaminated areas are sampled. They included office spaces, dining rooms, public spaces, living areas, storages, hotel rooms, and shuttle buses.

      Sample transfer and laboratory methods

      After collection of swabs, the samples are immediately transferred to a reference BSL-3 laboratory and processed. Samples were tested with Polymerase Chain Reaction (PCR) - Fluorescence Probing methods using Novel Coronavirus Nucleic Acid Detection Kit (BioGerm, Shanghai, China), targeting the ORF1ab and N genes to detect SARS-CoV-2 in the samples. Quantification of the viral load were estimated by the cycle threshold (Ct) value. Ct values are inversely correlated to viral loads. In this study, a sample was defined as positive if CT value for both ORF1ab and N genes are≤38.

      Surface cleaning and disinfection regimen

      Tasks were executed by trained cleaning teams. When no visible fomite is present, frequently touched surfaces inside the contaminated and potentially contaminated areas were cleaned twice daily using 1000mg/L available chlorine containing disinfectant, or wiped using 3% hydrogen peroxide disinfection wipes. When large amount of fomite is present, the fomite is first covered by dry paper towel and soaked in 5000mg/L chlorine disinfectant, removed carefully, and then cleaned as usual. Doffing rooms are cleaned after every 6-hour shift using 1000mg/L chlorine containing disinfectant, or 3% hydrogen peroxide disinfection wipes, and then ultraviolet lamps were turned on for 30 minutes.

      Statistics

      Descriptive statistics was used to represent data as numbers and percentages. Differences in the contamination rates between the areas were compared by Pearson's chi squared test. SPSS version 25 (IBM, SPSS Inc., Chicago, Illinois, USA) and GraphPad Prism 8.0 (GraphPad software company, San Diego, USA) were used for statistical analysis. P<0.05 was considered statistically significant.

      Results

      PPE and skin contamination

      A total of 120 PPE and skin samples were collected. Except for administrative staff and clinicians, regular shifts inside the contaminated areas were 6-hour long. Before swabbing the surfaces, the average time spent in the cabin was 290 (240-350) mins (Table 1). The overall viral RNA positive rate was 13.3% (16/120), with 13.6% (15/110) and 10.0% (1/10) for PPE surfaces and human skin, respectively. Among them, detection rate was highest for outer shoe cover (7, 70.0%), face shield (2, 20.0%), and coverall (2, 20.0%). None of the outer layer of gloves, N-95 respirators, scrub suit tops or trousers were positive (Figure 1). The overall contamination rate was 21.7% (13/60) on PPE surfaces before entering the first doffing room and 5.0% (3/60) on PPE or skin when inside the second doffing room. Average Ct values of PPE and skin surfaces positive was 37.84 ± 2.02 (Figure 2). Except for 1 pair of outer shoe cover and 1 coverall cap, Ct values were all >35.
      Table 1Healthcare workers investigated, average time spent in the contaminated areas, and PPE contamination rate.
      Healthcare workerTime (min)Sample (N)Positive sample (N)Positive rate (%)
      administration2352414.2
      clinician2402414.2
      nurse3502428.3
      cleaner34024312.5
      security34524937.5
      Figure 1
      Figure 1Contamination rate of SARS-CoV-2 on PPE surfaces and human skin.
      Figure 2
      Figure 2CT values of SARS-CoV-2 RNA on PPE, contaminated areas, and doffing rooms.
      Except for one administrative staff and one clinician, 80% of the HCWs sampled had at least one surface tested positive for virus RNA. The HCW with the most contamination tested positive for 41.7% (5/12) of the samples. Among different HCWs, PPE worn by security guards (9/24, 37.5%) and cleaners (3/24, 12.5%) were most contaminated, while those worn by clinicians and administrators (both 1/24, 4.2%) were least contaminated.

      Environmental surfaces

      Contaminated areas

      64 samples were collected inside the contaminated areas, overall contamination rate was 48.4%. Positive rates were 67.5% (27/40) in the patient occupied areas and 16.7% (4/24) in the public areas. Surfaces with the highest rate of contamination were bedrails (100.0%, 8/8), bedside floor (87.5%, 7/8), and chairs (75.0%, 6/8). The average CT value of was 36.75 ± 2.62 (Figure 2). 22.6% (7/31) of the samples had Ct values <35. After cleaning and disinfection, resampling at the previously positive sites were all negative.

      Doffing rooms

      120 environmental samples were collected from doffing rooms with an overall positive rate of 11.7%. Contamination rate of the first and second doffing rooms were 16.7% (10/60) and 6.7% (4/60) respectively (Figure 3). The highest percentage of viral RNA was found on the DR1 floor (50.0%, 5/10), the DR1 mirror (20.0%, 2/10), and the door handle entering DR2 (20.0%, 2/10). The average CT value of SARS-CoV-2 was 38.65 ± 1.59 (Figure 2). All the Ct values were >35. After cleaning and disinfection, resampling at the previously positive sites were all negative.
      Figure 3
      Figure 3Contamination rate of SARS-CoV-2 on doffing room environmental surfaces.

      Potentially contaminated areas

      302 samples were collected, including 117 from office rooms, 103 from public spaces, 26 from rest areas, 26 from shuttle buses, and 30 from hotels. All samples were negative for viral RNA.

      Discussion

      This current study analyzed contamination of SARS-CoV-2 on PPE and Fangcang hospital environmental surfaces, which has rarely been investigated. Results show that SARS-CoV-2 contaminates PPE as well as the surfaces of contamination and doffing areas. Contaminated areas where confirmed cases were staying have higher detection rates than doffing rooms (48.4% vs 11.7%, P<0.05). None of the surfaces in the potentially contaminated area was positive. After routine cleaning and disinfection, no viral RNA was detected in the repeat test.
      Healthcare workers are at the frontline in the fight against pandemics, hence bearing higher burden of infection. A meta-analysis showed that based on RT-PCR, the prevalence of COVID-19 in HCW was 11.0%. Severe complications occurred in 5% of HCWs infected and 0.5% died. Inpatient/ non-emergency ward staff and nurses are the most affected
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      • Deng R
      • et al.
      Contamination of SARS-CoV-2 in patient surroundings and on personal protective equipment in a non-ICU isolation ward for COVID-19 patients with prolonged PCR positive status.
      ,
      • Zhang S
      • Wang C
      • Lin M
      • Deng Q
      • Ye Y
      • Li Z
      • et al.
      Analysis of the Virus Contamination and Disinfection Effect in Isolation Ward of Patients With COVID-19.
      ,
      • Wang Y
      • Qiao F
      • Zhou F
      • Yuan Y.
      Surface distribution of severe acute respiratory syndrome coronavirus 2 in Leishenshan Hospital in China.
      . Currently, scientists are interested in development of anti-viral materials to reduce contact transmission of infectious viruses in clinical and public environments
      • Xue X
      • Ball JK
      • Alexander C
      • Alexander MR.
      All Surfaces Are Not Equal in Contact Transmission of SARS-CoV-2.
      . In our study, all the samples taken at the previously contaminated surfaces after cleaning and disinfection were negative, and no surface in the potentially contaminated areas were positive, proving the effectiveness and importance of infection prevention and control policies. Proper architectural layouts, hand hygiene, adequate personal protective equipment, cleaning and disinfection of the environments will continue to be valuable for the ongoing pandemic.
      The current study is not without limitations. First, only viral RNA was tested and no viral culture was done. Due to the high Ct values of the virus in positive samples, infectivity of contaminated surfaces could not be determined. Second, viral load in air samples was not detected. Second, the environmental temperatures and humidity, which may influence viral stability, were not recorded when swabs were taken. Finally, the Fangcang shelter hospitals included are reconstructed from existing venues, hence building layouts and structures are different. Experiences of these two hospitals may not directly apply to other Fangcang sites. Nevertheless, this study contributes to the understanding of PPE and environmental surface contamination in Fangcang hospitals during the Omicron wave of the pandemic.

      Conclusions

      In conclusion, SARS-CoV-2 contamination is widespread in Fangcang shelter hospital environmental surfaces, with the highest rate in patient occupied areas. PPE and doffing rooms are contaminated to different extent. Healthcare workers are at risk of hospital infection. Contaminated area samples, as well as samples of previously positive surfaces after cleaning and disinfection, are negative. This further illustrates the importance of implementing infection control policy.

      Footnote

      The authors have completed the STROBE reporting checklist.

      Conflicts of Interest

      All authors have completed the ICMJE uniform disclosure form. The authors have no conflicts of interest to declare.
      The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Ethical approval was not necessary due to the absence of patient involvement in this study.

      Funding

      This study is funded by “Evaluation of evidence-based hospital infection control” program by Chinese National Health Commission's Health Development Research Center.

      Conflicts of Interest

      All authors have completed the ICMJE uniform disclosure form. The authors have no conflicts of interest to declare.

      Acknowledgments

      Not applicable

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