Ultraviolet-C Irradiation, Heat, and Storage as Potential Methods of Inactivating SARS-CoV-2 and Bacterial Pathogens on Filtering Facepiece Respirators

Abstract

The arrival of SARS-CoV-2 to Aotearoa/New Zealand in February 2020 triggered a massive response at multiple levels. Procurement and sustainability of medical supplies to hospitals and clinics during the then upcoming COVID-19 pandemic was one of the top priorities. Continuing access to new personal protective equipment (PPE) was not guaranteed; thus, disinfecting and reusing PPE was considered as a potential alternative. Here, we describe part of a local program intended to test and implement a system to disinfect PPE for potential reuse in New Zealand. We used filtering facepiece respirator (FFR) coupons inoculated with SARS-CoV-2 or clinically relevant multidrug-resistant pathogens (Acinetobacter baumannii Ab5075, methicillin-resistant Staphylococcus aureus USA300 LAC and cystic-fibrosis isolate Pseudomonas aeruginosa LESB58), to evaluate the potential use of ultraviolet-C germicidal irradiation (UV-C) or dry heat treatment to disinfect PPE. An applied UV-C dose of 1000 mJ/cm2 was sufficient to completely inactivate high doses of SARS-CoV-2; however, irregularities in the FFR coupons hindered the efficacy of UV-C to fully inactivate the virus, even at higher UV-C doses (2000 mJ/cm2). Conversely, incubating contaminated FFR coupons at 65 °C for 30 min or 70 °C for 15 min, was sufficient to block SARS-CoV-2 replication, even in the presence of mucin or a soil load (mimicking salivary or respiratory secretions, respectively). Dry heat (90 min at 75 °C to 80 °C) effectively killed 106 planktonic bacteria; however, even extending the incubation time up to two hours at 80 °C did not completely kill bacteria when grown in colony biofilms. Importantly, we also showed that FFR material can harbor replication-competent SARS-CoV-2 for up to 35 days at room temperature in the presence of a soil load. We are currently using these findings to optimize and establish a robust process for decontaminating, reusing, and reducing wastage of PPE in New Zealand.

COVID-19 Pandemic: New Prevention and Protection Measures

“…For this reason, an Italian study suggests that efficient ventilation systems, compared with natural air exchange, can reduce the transmission of COVID-19 in schools by more than 80%, as well as improve air quality in terms of environmental contaminants and carbon dioxide concentration [24]. Lastly, the use of suitable instruments for sanitizing environments using chemicalphysical agents is becoming increasingly popular, including ozone gas, which has proved effective in removing pathogens including SARS-CoV-2 [25], the use of UV-C irradiation or dry heat treatment for the inactivation of both SARS-CoV-2 (Table 1) and other Lastly, the use of suitable instruments for sanitizing environments using chemicalphysical agents is becoming increasingly popular, including ozone gas, which has proved effective in removing pathogens including SARS-CoV-2 [25], the use of UV-C irradiation or dry heat treatment for the inactivation of both SARS-CoV-2 (Table 1) and other pathogens that could contaminate surfaces and PPE [26]. To avoid the indirect transmission of SARS-CoV-2, it is important to wash your hands properly, as they represent an indirect means of infection.…”

End-user acceptability of personal protective equipment disinfection for potential reuse: a survey of health-care workers in Aotearoa New Zealand

“…3 , 6 , 7 Calls to conserve PPE stocks, 8 reduce medical wastage, 5 and increase front-line supply have led to the rapid development of potential disinfection methods, including ultraviolet irradiation, dry and moist heat, and vaporised hydrogen peroxide. 7 , 9 , 10 , 11 , 12 The eventual increase in PPE supply led the US Food and Drug Administration to revoke all issued authorisations for PPE disinfection and reuse. 7…”

Prominent Anti-UVC Activity of Lignin Degradation Products

“…Coronavirus infects the transbronchial and alveolar epithelial cells, inducing lung damage and other organ impairments (2), and long-lasting spread of infection aggravates psychological and physical complications (3,4). Accordingly, the importance of environmental cleaning with sodium hypochlorite, disinfection with bactericidal and viricidal ultraviolet C (UVC) lamps in contaminated rooms and wearing masks has been designated as effective methods to reduce the risk of infection (5,6).…”