By William A. Rutala, PhD, MPH, CIC and David J. Weber, MD, MPH
In the recent years, we have witnessed the emergence of a number of new infectious diseases, many of which were major public health threats that were met with important infection prevention strategies. Now, an outbreak of novel coronavirus (SARS-CoV-2), which causes the coronavirus disease 2019 (abbreviated COVID-19) has spread rapidly, with cases confirmed in more than 140 countries.
Coronaviruses are a large family of viruses that cause an acute respiratory illness. Among these, MERS (Middle East respiratory syndrome), SARS (severe acute respiratory syndrome) and now COVID-19 may be transmitted from person to person, most commonly among close contacts (within about six feet), via respiratory droplets from coughs and sneezes. Due to the tenacity of the virus, it is possible that a person can acquire COVID-19 by touching a contaminated surface or object, and then touching his or her own mouth, nose, or eyes.
Over the past decade, there has been a growing appreciation that environmental contamination of hospital surfaces makes an important contribution to infection transmission for many pathogens. While the level of surface contamination with COVID-19 is not known, studies with other epidemiologically important pathogens have shown that disinfection leads to decreased transmission. Further, coronaviruses may survive on surfaces for hours to days, depending on temperature and humidity. Unfortunately, many studies have shown that disinfection of surfaces is suboptimal, and that effective disinfection requires not only an effective product, but also effective practice.
The combination of product and practice results in effective surface disinfection, including the reduction of risk via viral removal and/or inactivation of pathogens. The criticality of practice is highlighted by studies that demonstrate surface contamination with epidemiologically important pathogens is due to a failure to thoroughly disinfect surfaces rather than the use of inferior products or agents. While there are many factors that could influence the efficacy of disinfection, the surface must be completely and thoroughly wiped with an adequate number of antimicrobial wipes effective against the target pathogen (or harder to inactivate microorganisms) at a contact time specified by the label instructions.
The perfect disinfectant or product for healthcare disinfection has not been introduced; however, there is a wide array of excellent disinfectants that offer a range of characteristics. As of March 10, 2020, the CDC recommendation on disinfectant products for COVID-19 is to use an EPA-registered disinfectant on List N on the EPA website, which identifies which registered products are qualified under EPA’s emerging viral pathogens program for use against SARS-CoV-2.(2-4) This designation can be found on their Master Label.(3)
The rationale for this recommendation is if disinfectants inactivate harder to inactivate microorganisms (e.g., mycobacteria, non-enveloped viruses) than coronaviruses, they should be expected to inactivate COVID-19. The CDC(4) and the EPA(2) have ranked certain microorganisms by their tolerance or resistance to chemical disinfectants (i.e., the Spaulding classification model). In order of increasing resistance, these microorganisms are: lipid (i.e., enveloped) or medium-sized viruses (e.g., coronaviruses); vegetative bacteria (e.g., S. aureus); fungi (e.g., Candida, Aspergillus); non-lipid (i.e., non-enveloped) or small viruses (e.g., poliovirus, rhinovirus); mycobacteria (e.g., M. tuberculosis); coccidia (Cryptosporidium); and the most resistant, spores (e.g., C. difficile).(5) EPA further divided the viruses into three subgroups based on size and type of virus: enveloped viruses (such as coronavirus, easiest to inactivate); large (50-100nm) non-enveloped viruses (such as adenovirus and rotavirus, harder to inactivate than enveloped viruses); and small (<50nm) non-enveloped viruses (hardest to inactivate such as rhinovirus).(2) This hierarchy is used to determine a product’s anticipated efficacy against an emerging viral pathogen.(2)
SARS-CoV-2 is an enveloped virus and the easiest to inactivate of the three subgroups of viruses. Based on the EPA emerging viral pathogen criteria, an EPA-registered, hospital disinfectant must have a disinfectant efficacy claim against at least one small or one large non-enveloped virus to be eligible for use against an enveloped emerging viral pathogen.(2)
A thorough and complete application of an EPA List N-qualified disinfectant to surfaces, as well as good personal hygiene, including hand hygiene with a 60-90% alcohol-based product, or soap and water), minimize contact with your face, and respiratory hygiene/cough etiquette, should minimize transmission of viral respiratory pathogens such as COVID-19.
1. Weber DJ, Sickbert-Bennett EE, Kanamori H, Rutala WA. 2019. New and emerging diseases (Ebola, MERS-CoV, carbapenem-resistant Enterobacteriaceae, Candida auris): Focus on environmental survival and germicide susceptibility. Am J. Infect Control. 47:A29-A38.
2. Environmental Protection Agency. Process for Making Claims Against Emerging Viral Pathogen not on EPA-Registered Disinfectant Labels. https://www.epa.gov/pesticide-registration/guidance-registrants-process-making-claims-against-emerging-viral-pathogens
3. List N: Disinfectants for Use Against SARS-CoV-2 https://www.epa.gov/pesticide-registration/list-n-disinfectants-use-against-sars-cov-2
4. CDC: Interim Infection Prevention and Control Recommendations for Patients with Suspected or Confirmed Coronavirus Disease 2019 (COVID-19) in Healthcare Settings, March 10. https://www.cdc.gov/coronavirus/2019-ncov/infection-control/control-recommendations.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fcoronavirus%2F2019-ncov%2Fhcp%2Finfection-control.html
5. Rutala WA, Weber DJ, HICPAC. Guideline for disinfection and sterilization in healthcare facilities, 2008. https://www.cdc.gov/infectioncontrol/guidelines/disinfection/index.html
Rutala, PhD, MPH, CIC is the Director and co-founder of the North Carolina Statewide Program for Infection Control and Epidemiology (SPICE) and a Professor for the Division of Infectious Diseases at the University of North Carolina’s School of Medicine. He is a consultant to PDI Healthcare, a global company that provides a broad range of evidence-based Interventional Care, Environment of Care, and Patient Care solutions.
Weber, PhD, MPH, is a Professor of Medicine and Pediatrics in the University of North Carolina at Chapel Hill School of Medicine and a Professor of Epidemiology in the Gillings School of Global Public Health. Dr. Weber also serves as an Associate Chief Medical Officer and Medical Director Infection Prevention for UNC Hospitals. He is the Medical Director of the North Carolina Statewide Infection Control Program (SPICE), a Chair of UNC Biomedical IRB, and serves as the UNC Principle Investigator on the CDC sponsored Duke-UNC Epicenter. Dr. Weber is a consultant for PDI Healthcare.
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