Prevalence of Surface Contamination With SARS-CoV-2 in a Radiation Oncology Clinic

Abstract

This quality improvement study assesses surface contamination with SARS-CoV-2 in the radiation oncology department of a large COVID-19 referral center and discusses implications for routine cleaning and disinfecting practices.

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has resulted in a global pandemic. It is hypothesized that the virus spreads from person to person via respiratory droplets or contact with contaminated surfaces and objects.^1,2 Prior studies evaluating environmental contamination with SARS-CoV-2 have been conducted in health care settings treating patients known to have coronavirus disease 2019 (COVID-19)³; however, studies evaluating clinics that do not routinely treat patients with COVID-19 are lacking. Patients who have cancer and become infected with SARS-CoV-2 may have greater morbidity and mortality compared with the general public.⁴ Therefore, assessing the presence or absence of SARS-CoV-2 may provide important information for health care practitioners, patients, and their families, who must weigh the benefit of cancer treatment vs the risk of infection with SARS-CoV-2.

Methods

This quality improvement study took place in a radiation oncology department housed in a large tertiary care COVID-19 referral center in New Jersey. Every Monday, Wednesday, and Friday from May 1, 2020, to May 13, 2020, for a total of 6 days during the period of peak daily rate of COVID-19 diagnosis in New Jersey, environmental swabbing following World Health Organization protocols for COVID-19 surface sampling⁵ occurred at 4:30 pm before scheduled cleaning and disinfection services at 5 pm. Areas targeted for sampling were selected based on a higher risk of contamination because of frequency of use and patient contact. The immobilization mask of a patient with COVID-19 was also tested daily for 5 of the radiation treatments. Specimens were analyzed using real-time reverse transcription polymerase chain reaction analysis (detailed methods are given in the eAppendix in the Supplement). Because all biospecimens were obtained from surface sampling, the Rutgers University institutional review board deemed this study not to be human-subjects research and exempted it from the need for approval and informed patient consent.

Results

A total of 128 environmental samples were taken in the radiation oncology department, and 0 were positive for SARS-CoV-2 (Table). The environmental samples were organized into 3 categories: (1) 80 samples taken from patient areas, (2) 19 samples taken from staff areas, and (3) 29 samples taken from department equipment. Of the 128 samples, 15 were taken from objects used by the patient with COVID-19. None of these 15 samples were positive for SARS-CoV-2.

Table. Environmental Locations of Surface Swabs.

Location of samplesa	Samples obtained, No.
Patient areas	80
Sign-in computer keyboard and mouse	6
Chairs	15
Elevator	5
Floor	3
Buttons	2
Sinks	18
Toilets	18
Door handles	18
Staff areas	19
Computer keyboards and mice	4
Door handles	14
Control room floor	1
Department equipment	29
Blood pressure cuff	3
Linear accelerator	11
Computed tomography simulator	6
Immobilization maskb	9

^aA total of 15 environmental samples were taken from objects used by a patient with coronavirus disease 2019 (COVID-19), including 3 chair samples, 2 linear accelerator samples, 1 blood pressure cuff sample, and 9 immobilization mask samples.

^bAn immobilization mask was used during treatment of a patient with COVID-19. Over 5 days, swab samples were obtained from inside the mask near the mouth and nose before and after decontamination, for a total of 9 samples. One swab after decontamination was not obtained on the last day.

Discussion

Systematic testing of environmental surfaces in the radiation oncology clinic revealed no detectable SARS-CoV-2 RNA. Patients, staff, and physicians may be concerned about the potential risks of SARS-CoV-2 transmission in a hospital-based or outpatient clinic. Moreover, radiation oncology clinics are often housed in tertiary care hospitals that can have a high prevalence of patients with COVID-19, perhaps intensifying fears of infection. Many of the patients with cancer at our clinic have deferred or canceled their scheduled follow-up visits because of fears about COVID-19, and many radiation oncology clinics have experienced substantial decreases in patient volume because of the pandemic. Although rescheduling follow-up visits or converting selected follow-up visits and consultations to telemedicine is good practice during the pandemic, some patients or clinicians may delay or decline important cancer therapies that can substantially affect quality of life and cancer outcomes.⁶ We believe that appropriate patient care should not be delayed because of the pandemic. The results of this study suggest that following strict prevention protocols and routine cleaning and disinfecting seem adequate for limiting surface contamination with SARS-CoV-2.

This study had several limitations. No air samples were collected, because this study focused on surface contamination. In addition, because of the nature of environmental sampling, 100% of a surface could not be swabbed for analysis, which may have reduced sensitivity. Additional surface and air studies in varied environments are needed to better understand the role of environmental factors in spreading COVID-19.

Supplement.

eAppendix. Supplementary Methods for Sample Collection and Testing and Protocols to Prevent SARS-CoV-2 Contamination