Best Approach to Disinfecting Surfaces Amid Novel Coronavirus Outbreak

Human coronaviruses can remain active on surfaces such as metal, glass, or plastic for up to 9 days after exposure. The best way to deal with that problem is by cleaning those surfaces with a solution that’s 62% to 72% ethanol, .5% hydrogen peroxide, or 0.1% sodium hypochlorite within 1 minute of contamination, according to investigators with University Medicine Greifswald and Ruhr University Bochum in Germany whose study ran as an article in press in the Journal of Hospital Infection (JHI).

“Currently, the emergence of a novel human coronavirus, temporary named 2019-nCoV, has become a global health concern causing severe respiratory tract infections in humans,” the authors write. “Human-to-human transmissions have been described with incubation times between 2-10 days, facilitating its spread via droplets, contaminated hands or surfaces. We therefore reviewed the literature on all available information about the persistence of human and veterinary coronaviruses on inanimate surfaces as well as inactivation strategies with biocidal agents used for chemical disinfection, e.g. in healthcare facilities.”

Investigators looked at 22 studies that dealt with disinfection techniques for human coronavirus such as severe acute respiratory syndrome (SARS) coronavirus, middle east respiratory syndrome (MERS) coronavirus, or endemic human coronaviruses (HCoV).

To reach their conclusions, investigators conducted a Medline search, completed on January 28, using the terms “coronavirus,” “TGEV [transmissible gastroenteritis virus],” “MHV [murine hepatitis virus],” and “CCV [candidate vaccine virus].” The research team also conducted analysis on search terms “survival surface,” “persistence surface,” “persistence hand,” “survival hand,” “survival skin,” “persistence skin,” ‘virucidal,” “chemical inactivation,” “suspension test,” and “carrier test.” “Publications were included and results were extracted given they provided original data on coronaviruses on persistence (surfaces, materials) and inactivation by biocidal agents used for disinfection (suspension tests, carrier tests, fumigation studies),” the study states. 

The viral load of coronaviruses on inanimate objects during an outbreak is unknown, but it’s plausible that disinfection methods should help, especially when applied to frequently touched surfaces where you might expect the viral load to be most potent, according to the study. 

The investigators cite the World Health Organization, which advises “that environmental cleaning and disinfection procedures are followed consistently and correctly. Thoroughly cleaning environmental surfaces with water and detergent and applying commonly used hospital-level disinfectants (such as sodium hypochlorite) are effective and sufficient procedures.”

The investigators could not find data that describe how often and how much hands can be contaminated with coronaviruses after contacting an infected surface or patient. “In Taiwan, however, it was described that installing hand wash stations in the emergency department was the only infection control measure which was significantly associated with the protection [of] healthcare workers from acquiring the SARS-CoV, indicating that hand hygiene can have a protective effect,” the study states.

In addition, even though hand hygiene compliance appears to be significantly higher during an outbreak, there still seems to a lack of total buy-in among physicians, the study states, adding that transmission can be successfully prevented when appropriate measures are consistently performed. 

“Ethanol at concentrations between 62% and 71% reduced coronavirus infectivity within 1 min exposure time by 3.0–4.0 log₁₀,” according to the study. “Concentrations of 0.1- 0.5% sodium hypochlorite and 2% glutardialdehyde were also quite effective with > 3.0 log₁₀reduction in viral titre. In contrast, 0.04% benzalkonium chloride, 0.06% sodium hypochlorite and 0.55% ortho-phtalaldehyde were less effective.”

The endemic human coronavirus strain (HCoV-) 229E can remain infectious on certain surfaces for as little as 2 hours or up to 9 days.

“A higher temperature such as 30°C or 40°C reduced the duration of persistence of highly pathogenic MERS-CoV, TGEV, and MHV,” the study states. “However, at 4°C persistence of TGEV and MHV can be increased to ≥ 28 days.”