key: cord-253457-gawn4s9g
authors: Yau, Kevin; Muller, Matthew P.; Lin, Molly; Siddiqui, Naureen; Neskovic, Sanja; Shokar, Gagan; Fattouh, Ramzi; Matukas, Larissa M.; Beaubien-Souligny, William; Thomas, Alison; Weinstein, Jordan J.; Zaltzman, Jeffrey; Wald, Ron
title: COVID-19 Outbreak in an Urban Hemodialysis Unit
date: 2020-07-15
journal: Am J Kidney Dis
DOI: 10.1053/j.ajkd.2020.07.001
sha: 
doc_id: 253457
cord_uid: gawn4s9g

RATIONALE & OBJECTIVE: Hemodialysis patients are at increased risk for COVID-19 transmission due, in part, to difficulty maintaining physical distancing. Our hemodialysis unit experienced a COVID-19 outbreak despite following symptom-based screening guidelines. We describe the course of the COVID-19 outbreak and the infection control measures taken for mitigation. STUDY DESIGN: Retrospective cohort study SETTING & PARTICIPANTS: 237 maintenance hemodialysis patients and 93 hemodialysis staff at a single hemodialysis centre in Toronto, Canada. EXPOSURE: Universal screening of patients and staff with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). OUTCOMES: The primary outcome was detection of SARS-CoV-2 in nasopharyngeal samples from patients and staff using reverse transcriptase-polymerase chain reaction (RT-PCR) . ANALYTICAL APPROACH: Descriptive statistics were used for clinical characteristics and the primary outcome. RESULTS: Eleven (4.6%) of 237 hemodialysis patients and 11 of 93 (12%) staff members had a positive RT-PCR test for SARS-CoV-2. Among individuals testing positive, 12 of 22 (55%) were asymptomatic at time of testing, and 7 of 22 (32%) were asymptomatic for the duration of follow-up. One patient was hospitalized at the time of SARS-CoV-2 infection and four additional patients with positive tests were subsequently hospitalized. Two patients (18%) required admission to the intensive care unit. After 30 days follow-up no patients had died or required mechanical ventilation. No hemodialysis staff required hospitalization. Universal droplet and contact precautions were implemented during the outbreak. Hemodialysis staff with SARS-CoV-2 infection were placed on home quarantine regardless of symptom status. Patients with SARS-CoV-2 infection including asymptomatic individuals were treated with droplet and contact precautions until confirmation of negative SARS-CoV-2 RT-PCR testing. Analysis of the outbreak identified two index cases with subsequent nosocomial transmission within the dialysis unit and in shared shuttle buses to the hemodialysis unit. LIMITATIONS: Single centre study. CONCLUSIONS: Universal SARS-CoV-2 testing and universal droplet and contact precautions in the setting of an outbreak appeared to be effective in preventing further transmission.

Hemodialysis patients are at increased risk for COVID-19 transmission due, in part, to difficulty maintaining physical distancing. Our hemodialysis unit experienced a COVID-19 outbreak despite following symptom-based screening guidelines. We describe the course of the COVID-19 outbreak and the infection control measures taken for mitigation.

Study Design: Retrospective cohort study.

Setting & Participants: 237 maintenance hemodialysis patients and 93 hemodialysis staff at a single hemodialysis centre in Toronto, Canada.

Exposure: Universal screening of patients and staff with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Outcomes: The primary outcome was detection of SARS-CoV-2 in nasopharyngeal samples from patients and staff using reverse transcriptase-polymerase chain reaction (RT-PCR) .

Analytical Approach: Descriptive statistics were used for clinical characteristics and the primary outcome. Conclusions: Universal SARS-CoV-2 testing and universal droplet and contact precautions in the setting of an outbreak appeared to be effective in preventing further transmission. Eleven of 237 (4.6%) hemodialysis patients and 11 of 93 (12%) of staff tested positive for COVID-19. Notably 55% of those testing positive were asymptomatic at the time of testing. This study demonstrates the importance of universal testing in stopping the spread of COVID-19 during an outbreak.

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has prompted widespread restrictions on ambulatory inperson healthcare encounters. However, patients with kidney failure who receive maintenance hemodialysis must continue to receive life-sustaining treatment, typically three times per week. 1 Hemodialysis attendance, including travel to and from the centre, entails close interaction with individuals who may be infected with SARS-CoV-2. 2 Concerns regarding viral acquisition are heightened by the fact that hemodialysis recipients have multiple risk factors for severe COVID-19. 3 The US Centers for Disease Control and Prevention and the American Society of Nephrology have issued interim guidance to prevent COVID-19 in outpatient hemodialysis units including screening protocols to identify symptomatic patients or healthcare workers. 4 However, a recent outbreak at a skilled nursing facility has led to increasing recognition of the role of asymptomatic individuals in disease transmission. 5 We report the dynamics and course of a recent COVID-19 outbreak affecting patients and staff at an urban hemodialysis unit.

St. Michael's Hospital is an academic medical centre in Toronto, Canada, where 240 patients receive maintenance hemodialysis. The hemodialysis unit is divided into two large rooms on the same floor down the hall from each other. Each room is further subdivided into three clusters of 4-8 dialysis stations referred to as "pods". Hemodialysis staff are assigned to work with patients in a specific pod although they may assist patients in other pods.

Hemodialysis patients typically dialyze three times a week on a morning, afternoon, evening, or overnight shift.

Prior to the outbreak, physical distancing was implemented in the waiting room and two layers of pre-screening for symptoms were conducted prior to dialysis: the first by telephone on the day prior to the scheduled dialysis session and the second, following the patient's arrival in the dialysis unit waiting area. Dialysis pre-screening involved recording tympanic temperature, This study was approved by the Unity Health Research Ethics Board. Patient and staff consent was waived due to infection control measures with the exception of the two COVID-19 patients admitted to the intensive care unit from whom informed consent was obtained. The reporting of this study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. 6 Two patients were diagnosed with COVID-19 on April 7, 2020. The detection of three additional cases on April 9, 2020 led to the declaration of an outbreak. Investigation efforts were undertaken by an outbreak management team that was led primarily by the hospital Infection Prevention and Control (IPAC) team in collaboration with public health authorities, and the hemodialysis unit. Between April 11, 2020 and April 22, 2020, all remaining patients and staff who interacted with hemodialysis patients were tested for SARS-CoV-2 by nasopharyngeal swabs.

SARS-CoV-2 nasopharyngeal swabs were collected by personnel who had received instruction in the proper technique. Nasopharyngeal swabs were performed by physicians, nurse practitioners, and staff from the hospital's COVID-19 Assessment Centre under droplet and contact precautions in the hemodialysis unit with curtains drawn around the dialysis station at which the patient was being swabbed. SARS-CoV-2 testing was performed with the NucliSENS easyMAG extractor/ABI QuantStudio5 platform using the Altona RealStar SARS-CoV-2 RT-PCR Kit 1.0. Hemodialysis unit staff who were sent for screening included physicians, nurse practitioners, nurses, dialysis support assistants, medical imaging technologists, allied health, porters, and environmental services staff. Universal droplet and contact precautions including gloves, face shields, surgical masks, and isolation gowns were initiated on April 9, 2020 on the dialysis shift with known affected patients and expanded to the entire dialysis unit on April 10, 2020.

Contact tracing was a joint undertaking led by IPAC and the hospital's occupational health department, with IPAC taking the primary lead for patient contact tracing and occupational health for staff contact tracing. Public health authorities conducted contact tracing for family members and community contacts. This included symptom screening of contacts and ongoing monitoring for 14 days post-exposure. All symptomatic contacts were referred for testing but asymptomatic household contacts were not routinely tested as per public health protocols at the time. Hemodialysis staff testing positive for COVID-19 had information recorded regarding dates worked, symptoms, date of symptom onset, duration of symptoms, locations worked while symptomatic, locations worked during 48 hours to 2 weeks prior to symptom onset, personal protective equipment usage, and recent contacts including patient interactions.

Universal SARS-CoV-2 testing, clinical characteristics and outcomes Among 237 hemodialysis patients who agreed to testing (99%), 11 (4.6%) tested positive for SARS-CoV-2, while 11 of 93 (12%) staff tested were found to be positive (Figure 1) . At the time of testing, six (55%) patients and six (55%) staff positive for SARS-CoV-2 were asymptomatic. Three patients (27%) and four staff (36%) remained asymptomatic for the entire duration of follow-up (Table 1) . Among the 11 patients with COVID-19 the median age was 66 (IQR, 63-72), six (55%) were male, and seven (64%) were dialyzed on the same shift ( Table 2) . sharing the shuttle bus with other infected patients. These two patients took the same shuttle bus service to the same hemodialysis shift as other infected patients but dialyzed in different parts of the hemodialysis unit, suggesting that they acquired COVID-19 outside of the hemodialysis unit.

Response to the outbreak Following declaration of the outbreak, additional infection control measures were implemented. Droplet and contact precautions were mandated for all patient contact until outbreak resolution. SARS-CoV-2-positive patients were cohorted in a dedicated waiting room that was subjected to thorough cleaning after the patient's departure. The number of environmental services staff was escalated to increase the frequency of unit cleaning. "Safety coaches" were deployed to the hemodialysis unit to provide feedback to staff regarding proper usage of personal protective equipment. All inpatients were dialyzed in their hospital room regardless of COVID-19 status. Porters were required to utilize a face shield and mask when transporting dialysis patients, and universal masking of patients was implemented. Patient movement between dialysis shifts was restricted and extra dialysis sessions (e.g. a Saturday session for a patient who normally dialyzes on Monday, Wednesday, and Friday) were put on hold in order to limit a given patient's exposure to additional cohorts of patients.

Patients with confirmed SARS-CoV-2 infection including asymptomatic individuals were dialyzed in a dedicated room separate from the main hemodialysis unit for the duration of their infection and maintained on droplet and contact precautions. Repeat testing was performed following symptom resolution and a minimum of 14 days from symptom onset. Two negative SARS-CoV-2 nasopharyngeal swabs within a 24 hour period were required prior to the patient being allowed to return to his/her regular station in the dialysis unit. Among the six patients with a persistently positive SARS-CoV-2 nasopharyngeal swab, five (83%) were hospitalized ( Table   3) . Hemodialysis staff with confirmed SARS-CoV-2 including those who were asymptomatic, were asked to self-isolate at home. Five hemodialysis staff were allowed to return to work following symptom resolution and documentation of two negative SARS-CoV-2 nasopharyngeal swabs performed 14 days from symptom onset. The return to work policy for hemodialysis staff was revised by IPAC on May 7, 2020 to no longer require repeat SARS-CoV-2 testing.

Following this change in policy, the remaining six hemodialysis staff with SARS-CoV-2 infection were allowed to return to work 14 days from symptom onset assuming symptoms had resolved, without demonstration of a negative SARS-CoV-2 nasopharyngeal swabs.

The outbreak was declared resolved on May 10, 2020 by IPAC on the basis of no new cases being detected in the hemodialysis unit over a 14 day period. Since the outbreak was declared over, only individuals who reported symptoms during the pre-dialysis screening process were tested. No additional patient or staff cases have been identified as of June 19, 2020.

Although droplet and contact precautions were rescinded in the hemodialysis unit, masks remain mandatory throughout the hospital and face shields must be worn by all hemodialysis staff in the course of patient care. Infection control authorities concluded that SARS-CoV-2 transmission during an outbreak at the St. Michael's Hospital hemodialysis unit was likely to have originated from two index cases. Patient #1 acquired the virus through an outbreak at a skilled nursing facility and hemodialysis staff #1 likely acquired the virus in the community. Subsequent transmission likely occurred from patient-patient interactions or indirectly through staff. Later transmission likely occurred through a shared bus shuttle service to and from dialysis despite implementation of universal droplet and contact precautions within the hemodialysis unit. Our hemodialysis unit is divided into a two separate rooms, each which is further subdivided into three clusters of dialysis chairs referred to as pods. Dates on the arrows reflect the day of hypothesized transmission.

Mitigating Risk of COVID-19 in Dialysis Facilities

Clinical Characteristics of and Medical Interventions for COVID-19 in Hemodialysis Patients in Wuhan

Mild or Moderate Covid-19

COVID-19 and Dialysis Units: What Do We Know Now and What Should We Do?

Asymptomatic Transmission, the Achilles' Heel of Current Strategies to Control Covid-19

Strengthening the reporting of observational studies in epidemiology (STROBE) statement: guidelines for reporting observational studies

Maintenance Hemodialysis and Coronavirus Disease 2019 (COVID-19): Saving Lives With Caution, Care, and Courage

Epidemiology of COVID-19 in an Urban Dialysis Center

Serologic Detection of SARS-CoV-2 Infections in HD Centers Population

False Negative Tests for SARS-CoV-2 Infection -Challenges and Implications

Acknowledgements: We would like to thank all hemodialysis staff at St. Michael's Hospital for their dedication to patient care during the COVID-19 pandemic.Peer Review: Received May 25, 2020. Evaluated by 2 external peer reviewers, with direct editorial input from a Statistics/Methods Editor, an Associate Editor, and the Editor-in-Chief.Accepted in revised form July 2, 2020.