key: cord-0716862-f3rt1fyk
authors: Ge, Tianxiang; Lu, Ye; Zheng, Shufa; Zhuo, Lixin; Yu, Ling; Ni, Zuowei; Zhou, Yanan; Ni, Lingmei; Qu, Tingting; Zhong, Zifeng
title: Evaluation of disinfection procedures in a designated hospital for COVID-19
date: 2020-08-22
journal: Am J Infect Control
DOI: 10.1016/j.ajic.2020.08.028
sha: 1be68e58a04431f405ab55995323b4461bd5c0f5
doc_id: 716862
cord_uid: f3rt1fyk

BACKGROUND: Coronavirus disease 2019 (COVID-19) has spread globally and been a public health emergency worldwide. It is important to reduce the risk of healthcare associated infections among the healthcare workers and patients. This study aimed to investigate the contamination of environment in isolation wards and sewage, and assess the quality of routine disinfection procedures in our hospital. METHODS: Routine disinfection procedures were performed three-times a day in general isolation wards and six-times a day in isolated ICU wards in our hospital. Environmental surface samples and sewage samples were collected for viral RNA detection. SARS-CoV-2 RNA detection were performed with quantitative reverse transcription PCR (qRT-PCR). RESULTS: A total of 163 samples were collected from February 6th to April 4th. Among 122 surface samples, two were positive for SARS-CoV-2 RNA detection. One was collected from the flush button of the toilet bowl, and the other was collected from a hand-basin. Although 10 of the sewage samples were positive for viral RNA detection, all positive samples were negative for viral culture. CONCLUSION: These results revealed the routine disinfection procedures in our hospital were effective in reducing the potential risk of healthcare associated infection. Two surface samples were positive for viral detection, suggesting that more attention should be paid when disinfecting places easy to be ignored.

Coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has globally spread and been declared as a pandemic by the World Health Organization (WHO) on March 11 th , 2020 [1] . COVID-19 has been spreading fast because people are generally susceptible. The common symptoms of COVID-19 patients include fever, fatigue, dry cough, and the computed tomography scans showed bilateral patchy shadows or ground glass opacity in the lungs, while headache, dizziness, and gastrointestinal symptoms including abdominal pain, diarrhea, and vomiting are less common symptoms [2] . The predicted incubation time of SARS-CoV-2 is 14 days, which may lead to a high rate of asymptomatic and subclinical infection among susceptible individuals, and people may get infected and be unaware of how or where it came from [3] . Thus, effective interventions should be taken to break the chain of transmission of SARS-Cov-2.

Both confirmed patients and suspected individuals have potential to transmit the virus, since the viral shedding of asymptomatic patients have already been confirmed [4, 5] . The transmission of the virus is mainly by the respiratory droplets or by direct and indirect contact, and the viable SARS-CoV-2 particles could be detected for more than 1.5~3 hours in aerosols under experimental conditions [6, 7] . The droplets produced when COVID-19 patients coughed or sneezed could be transported over a long distance by airflow before settled on the surface, and the SARS-CoV-2 could stay viable for a long time after the droplets completely evaporated [8, 9] . The RNA purification is the gold standard for the detection of SARS-CoV-2 in samples, and the existence of SARS-CoV-2 RNA in the specimens of respiratory tract and feces of confirmed and asymptomatic patients have been confirmed by several researches [10, 11] . Therefore, the environmental contamination could be attributable to direct contact with infected respiratory fluids, feces and depositing of aerosol particles [12] . These results also indicate that sewage of the hospital could also be contaminated by COVID-19 patients' bodily fluids.

Many researches have reported the contamination of air and surfaces by SARS-CoV-2, emphasizing the importance of cleaning and disinfection in hospitals, despite the viability of the virus still need to be investigated [12] [13] [14] [15] . Due to lack of personal protective equipment (PPE), a lot of healthcare workers (HCWs) became infected during period of COVID-19 patients' care at the early stage of this pandemic [16] . Thus, disinfection procedures are highlighted in mitigating healthcare associated infections (HAIs).

In this study, we enlarged the sample size and enhanced the sampling frequency to evaluate the quality of routine disinfection in isolation wards and sewage. In order to identify potential risk factors, places easy to be ignored were also sampled after disinfection, such as door handles, Flush button of the toilet bowl and hand-basin.

This study was conducted in Zhijiang Campus, the First Affiliated Hospital of Zhejiang University, China. The hospital was originally a Grade 3A hospital and became one of designated hospitals for COVID-19 patients in Zhejiang province since the outbreak of COVID-19. The isolation wards were separated into three parts and two passages, including a contaminated area, a semi-contaminated area, and a clean area. One passage was for patients, and the other was for medical stuff. The arrangement of the isolation wards was described in detail in the article we published before [17] . And the preprocessing disinfection equipment (Tianxingjian water-treatment Co., Ltd., Zhejiang, China) were added into the sewage disinfection system of the hospital. When compared with previous study, more places that could be potentially contaminated by COVID-19 patients were sampled for viral RNA detection, such as the flush button of the toilet bowl, medical refuse transfer trolley, elevators, and the examination rooms for these patients. Both respiratory and feces samples were collected during the hospitalization of COVID-19 patients and after their discharge to evaluate the quality of our disinfection procedures.

Patients with COVID-19 were confirmed by the positive polymerase chain reaction (PCR) results of respiratory samples. Both respiratory samples and feces samples were collected for PCR test during their hospitalization.

Suspected individuals were hospitalized in single-person rooms with dedicated toilets. Confirmed patients were hospitalized into cohort-rooms with shared toilets in general isolation wards or isolation intensive care unit (ICU) wards based on severity of illness. In a cohort-room, beds were spaced at least 1.2 meters apart, and up to three patients could be hospitalized in at a time ( Figure   1 ).

Routine disinfection procedures were performed three-times a day in general isolation wards and six-times a day in isolated ICU wards. 

The environmental surface sampling was conducted in isolation wards where confirmed patients were hospitalized in. We collected samples from high-touch surfaces of the contaminated area, the semi-contaminated area and the clean area in both general isolation wards and isolation ICU wards, including beeper, flush button, hand-basin, door handle, bedside table, medical surface, elevator button, desktop, computer mouse and keyboard, telephone and others. These samples were collected two hours after the routine cleaning and disinfection.

We also collected samples from medical equipment and other high-touch surfaces in examination rooms for COVID-19 patients after terminal disinfection procedures.

ClassiqSwabs (Copan Flock Technologies, Brescia, Italy) were used for environmental surfaces sampling, and universal transport medium were used for sample transportation and storage before performing the PCR tests.

Sewage from the preprocessing disinfection equipment and the final disinfection pool were collected for viral RNA detection. Briefly, 1ml sewage sample was centrifuged (12000×g for 5 mins at 4 ℃) to remove the solids, and 300 μl supernatant was collected for RNA extraction and PCR assay. Of the paired sewage samples collected from the preprocessing disinfection equipment, six (6/14) from the inlets and four (4/14) from the outlets were found to be positive for SARS-CoV-2 RNA testing ( Table 2 ). The viral culture of these samples was negative. All samples collected from the final disinfection pool were negative for SARS-CoV-2 RNA testing.

All samples collected from the examination rooms after the terminal disinfection were negative for SARS-CoV-2 RNA testing (Table 3 ).

It was reported that the COVID-19 has caused more than 82,341 infections across China, over 3000 of which were in HCWs by April 15, 2020 [16] . Most of the infected HCWs were confirmed at the early stage of this pandemic, when environmental cleaning and disinfection protocols were not established and HCWs were not aware of the potential risk of getting infected [18] .

A research of the stability of SARS-CoV-2 indicated that the virus could be detected in 4 hours on copper and 24 hours on cardboard, while it could be detected up to 72 hours after application to plastic and stainless steel [7] .

Despite of the human-to-human transmission, the contact of contaminated surfaces may contribute to the HAIs among the HCWs and patients [14] . Therefore, the environmental cleaning and disinfection protocols were extremely important in preventing the HAIs.

All Covid-19 patients and suspected individuals without mechanical ventilation were wearing surgical masks during their hospitalization in our hospital. And alcohol-based hand hygiene sanitizer dispensers were placed nearby the beds in the patient's room. Since the environment could become contaminated with the virus, touching infected patients or patient surroundings could be a possible route for SARS-CoV-2 transmission, which would eventually cause the HAIs among patients and HCWs. It was important to perform the hand hygiene to stop the spread of the virus from one place to another. In our hospital, PPE was used by HCWs in isolation wards, including N95 masks, gloves and disposable isolation gowns. The PPE was removed in the removal area, thus HCWs were required to perform hand hygiene without removing gloves in isolation wards. The key moments and procedures for hand hygiene were in accordance with the WHO guidelines [19] . Combined with routine disinfection, these procedures were proved to be effective according to the As the epidemic had been brought under control in China, few new cases were found in Zhejiang province, and patients with COVID-19 were recovered and discharged from our hospital. Terminal disinfection and environmental sampling was required for the isolation wards and examination rooms in order to provide medical services for non-COVID-19 patients. The disinfection procedures for examination rooms were consistent with the procedures for the isolation wards. These areas could not be used for non-COVID-19 patients until all the environmental samples collected were negative for SARS-CoV-2 RNA detection. In this study, surface samples collected from the examination rooms were all negative for SARS-CoV-2 RNA detection, and the samples collected from isolation wards and other places were also negative for viral RNA detection, which indicated that the terminal disinfection was effective.

The presence of SARS-CoV-2 RNA in feces of COVID-19 patients had been widely reported [20] [21] [22] , which meant the virus could also be detected in the sewage. It had been verified by some researches about the wastewater in USA, France, Italy and China [17, [23] [24] [25] . Individuals could get infected with sewage which contained the SARS-CoV-2 virus via the fecal-oral route, in spite of the viability of SARS-CoV-2 virus in sewage was still unknown [26] . To our knowledge, few studies have provided insights into whether the contaminated sewage could cause COVID-19 [27] .

In order to sufficient inactivate SARS-CoV-2 virus in the sewage drained into urban sewage, the preprocessing disinfection equipment were added into the sewage disinfection system of the hospital. Although some sewage samples collected from the inlets and outlets were positive, the results of viral culture for these samples were all negative. This result indicated there was no viable virus due to disinfection in the preprocessing disinfection equipment. And all samples from the final disinfection pool were negative. These results indicated the disinfection of patients' feces was necessary to reduce the potential risk of SARS-CoV-2 transmission.

Our study had several limitations. First, we did not collect the air samples due to the lack of air sampling machine. Other researches had revealed the presence of SARS-CoV-2 RNA in aerosol, which indicated the air could be contaminated by the virus, and patients could be infected in the isolation wards [12, 28] . Second, the positive samples of surfaces were determined by PCR tests, while the ability of virus could not be determined. Third, we collected the samples at single time point in the disease process of individual patients, and did not investigate whether there is any relationship between the levels of environmental contamination and the disease.

In conclusion, during the COVID-19 pandemic, our hospital implemented a set of disinfection procedures to reduce the potential risk of HAIs via the directly contact of contaminated surfaces. The environmental surveillance of SARS-CoV-2 in this study revealed our routine disinfection procedures were effective, despite two samples tested positive for SARS-CoV-2 RNA. No HAI of COVID-19 were detected in our hospital. Additionally, the disinfection of patients' feces was sufficient for the inactivation of SARS-CoV-2 in the sewage drained from the hospital. These findings indicated the disinfection procedures performed in our hospital were effective in preventing the HCWs from getting infected. Further studies with larger sampling size were required to clarify the relationship between the levels of contamination and the disease. 

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