copper

A little good news on the COVID-19 front: yes, you can kill the virus on surfaces, with easily available disinfectants.

Copper surfaces, silver particles, alcohol-based disinfectants, and UV light will kill the virus. Frequently touched items, especially in public places, should probably just be irradiated with UVC light and/or coated with copper as a routine prevention measure.

(Regular UV light is an effective disinfectant but can also blind people and burn skin; UVC is a shorter wavelength, equally effective against microbes but not harmful to eyes or skin.)

Do Copper Surfaces Kill/Inactivate Coronaviruses?

In an experiment with aerosolized SARS-CoV-2 and SARS-CoV-1, at 21-23 degrees C and 40% humidity, both reached undetectable levels within 8 hours exposure to copper; by contrast, they lasted 72 hours on stainless steel and plastic.[1]

H1N1 influenza, which was another pandemic virus, though not a coronavirus, lasted significantly less time on copper than stainless steel; 10^5 viable viruses after 24 hours on stainless steel vs. 10^2 viable viruses after 2 hours on copper.[2]

Human coronavirus 229E remains infectious on plastic, ceramic, glass, and stainless steel for at least 5 days, was inactivated in less than 5 minutes on copper and brass when applied dry, and inactivated in less than an hour when applied in solution to metal alloys containing >75% copper.[4]

Using copper-coated surfaces in real-world environments reduces microbial contamination. In 5 residential healthcare facilities, where half of the doorknobs and handrails were coated with copper alloys while half were not, the bacterial concentration was significantly (p < 0.0001) lower on the copper-coated doorknobs and handrails.[5]  Similarly, when weights and grips in a gym were coated with copper alloy or left as rubber or stainless steel, the bacterial concentrations on the copper-coated surfaces were 94% lower than the controls.[6]

Silver Ion Zeolites as Anti-Microbial Surfaces

Commercially available silver zeolite powder (AgION powder, manufactured by Sinanen Co.) completely inactivated SARS-CoV at concentrations above 375 mg/L.  

Zeolites are fine, talc-like powders that can be incorporated into coatings to produce antimicrobial surfaces; the FDA has approved zeolites for use in food packaging.[3]

Disinfectants

In a study of 7 disinfectant liquids on the SARS coronavirus, including several with >80% ethanol as active ingredient, all of them significantly reduced SARS concentrations, by a factor of at least 1000.[7]

70%+ ethanol was effective at reducing (by a factor of >1000) the infectivity of both SARS and MERS coronaviruses; so was 50%+ 2-propanol, hydrogen peroxide, glutaraldehyde, formaldehyde, and povidone iodine. Chlorhexidine was not effective.[9]

In a study of human coronaviruses 229E and OC43, soap, bleach, and Proviodine (the active ingredient was iodine) all completely inactivated the viruses.[8]

Axe dishwashing detergent, sodium hypochlorite solution, and the disinfectant Virkon S, all killed SARS-CoV virus by a factor of at least 1000.[10]

Against two coronaviruses, mouse hepatitis virus and transmissible gastroenteritis virus, a solution of 70% ethanol reduced viral infectivity by a factor of >1000; phenolic, sodium hypochlorite, and orthopthalaldehyde did not.[11]

UVC Radiation

Exposure of SARS virus to UVC radiation for six minutes results in a 400-fold reduction in infectivity.  UVA and gamma radiation did not affect infectivity.[12] Another study of SARS found 1000-fold inactivation from 15 minutes of exposure to UVC.[13]

A study of Ebola virus and MERS virus found that UVC light at >0.1 J/cm^2 reduced infectivity more than 5000-fold in both.  Methylene blue plus light at >30 J/cm^2 also reduced infectivity 2000-fold in both.[14]

Far-UVC light (207-222 nm) inactivates bacteria without harm to human skin.  It also reduces H1N1 infectivity by 100-fold at low doses: 2 mJ/cm^2.[15]

222-nm far-UVC light applied to a mouse wound where MRSA bacteria had been spread reduced skin bacteria concentrations by >1000-fold, just like 254-nm conventional antimicrobial UV irradiation, but only the 254-nm light increased skin thickness significantly ( a measure of skin damage.)[16]

References

[1]van Doremalen, Neeltje, et al. “Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1.” New England Journal of Medicine (2020).

[2]Otter, J. A., et al. “Transmission of SARS and MERS coronaviruses and influenza virus in healthcare settings: the possible role of dry surface contamination.” Journal of Hospital Infection 92.3 (2016): 235-250.

[3]Feied, Craig. “Novel Antimicrobial Surface Coatings and the Potential for Reduced Fomite Transmission of SARS and Other Pathogens.” (2004): 1-22.

[4]Warnes, Sarah L., Zoë R. Little, and C. William Keevil. “Human coronavirus 229E remains infectious on common touch surface materials.” MBio 6.6 (2015): e01697-15.

[5]Colin, Marius, et al. “Copper alloy touch surfaces in healthcare facilities: an effective solution to prevent bacterial spreading.” Materials 11.12 (2018): 2479.

[6]Ibrahim, Zina, et al. “Reduction of bacterial burden by copper alloys on high-touch athletic center surfaces.” American journal of infection control 46.2 (2018): 197-201.

[7]Rabenau, H. F., et al. “Efficacy of various disinfectants against SARS coronavirus.” Journal of Hospital Infection 61.2 (2005): 107-111.

[8]Sizun, J., M. W. N. Yu, and P. J. Talbot. “Survival of human coronaviruses 229E and OC43 in suspension and after drying onsurfaces: a possible source ofhospital-acquired infections.” Journal of Hospital Infection 46.1 (2000): 55-60.

[9]Kampf, Günter, et al. “Persistence of coronaviruses on inanimate surfaces and its inactivation with biocidal agents.” Journal of Hospital Infection (2020).

[10]Lai, Mary YY, Peter KC Cheng, and Wilina WL Lim. “Survival of severe acute respiratory syndrome coronavirus.” Clinical Infectious Diseases 41.7 (2005): e67-e71.

[11]Hulkower, Rachel L., et al. “Inactivation of surrogate coronaviruses on hard surfaces by health care germicides.” American journal of infection control 39.5 (2011): 401-407.

[12]Darnell, Miriam ER, et al. “Inactivation of the coronavirus that induces severe acute respiratory syndrome, SARS-CoV.” Journal of virological methods 121.1 (2004): 85-91.

[13]Darnell, Miriam ER, and Deborah R. Taylor. “Evaluation of inactivation methods for severe acute respiratory syndrome coronavirus in noncellular blood products.” Transfusion 46.10 (2006): 1770-1777.

[14]Eickmann, Markus, et al. “Inactivation of Ebola virus and Middle East respiratory syndrome coronavirus in platelet concentrates and plasma by ultraviolet C light and methylene blue plus visible light, respectively.” Transfusion 58.9 (2018): 2202-2207.

[15]Welch, David, et al. “Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases.” Scientific Reports 8.1 (2018): 1-7.

[16]Ponnaiya, Brian, et al. “Far-UVC light prevents MRSA infection of superficial wounds in vivo.” PloS one 13.2 (2018).