[Evidence summary:] How long can the COVID-19 virus exist on surfaces? What role do contaminated surfaces play in the chain of transmission? What infection control precautions should be implemented? [v2.0]

In most instances, coronaviruses are believed to be transmitted through large respiratory droplets from person to person, through inhalation or deposition on mucosal surfaces.Other routes implicated in transmission of coronaviruses include contact with contaminated fomites ie surfaces or objects which may transmit a disease to a new host and inhalation of aerosols produced during aerosol generating procedures4.According to the Centers for Disease Control (CDC)transmission occurs much more commonly through respiratory droplets than through fomites8, 9.They caution that whilst exposure to contaminated surfaces is not thought to be the main way the virus spreads, there is still much to learn about modes of transmission9.The viruses and bacteria that cause acute respiratory infections (ARIs)can survive in the environment for variable periods of time: hours to days2. Kampf et al reveal that human coronaviruses such as Severe Acute Respiratory Syndrome (SARS) coronavirus, Middle East Respiratory Syndrome (MERS)coronavirus or endemic human coronaviruses (HCoV)can persist on inanimate surfaces such as metal, glass or plastic for up to 9 days12. Research reported by Van Doremalen et al showed that SARS-CoV-2 was more stable on plastic and stainless steel than on copper and cardboard,and that viable virus was detected up to 72 hours after application to these surfaces although the virus titer was greatly reduced15.The same study indicates that aerosol and fomite transmission of SARS-CoV-2 is plausible, since the virus can remain viable and infectious in aerosols for hours and on surfaces up to days15.Ren’s study adds that the persistence time on inanimate surfaces varied from minutes to up to one month, depending on environmental conditions,and that SARS-CoV-2 can be sustained in air in closed unventilated buses for at least 30 minutes without losing infectivity20.It is worth noting that in a Q and A interview, Carolyn Machamer, Professor of Cell Biology,whose lab at the Johns Hopkins School of Medicine has studied the basic biology of coronaviruses for years,states: “What's getting a lot of press and is presented out of context is that the virus can last on plastic for 72 hours which sounds really scary. But what's more important is the amount of the virus that remains. It's less than 0.1% of the starting virus material. Infection is theoretically possible but unlikely at the levels remaining after a few days. People need to know this37.”Furthermore,William Keevil, Professor of Environmental Healthcare at the University of Southampton,states that there is a danger of drawing too many conclusions about the likely progression of the virus on a surface when there are so many different and in some cases unique variables between the materials38.Virus particles in the air and on fomites are exposed to a range of environmental conditions that influence their persistence. Relative humidity, fomite material and air temperature can greatly impact enveloped virus inactivation rates36.The importance of indirect contact transmission involving contamination of inanimate surfaces is uncertain and warrants further study. To reduce the risk of infection through fomites, it is essential to establish procedures for the correct disinfection of environments that could have been contaminated with SARS-CoV-25. An effective surface disinfection may help to ensure an early containment and prevention of further viral spread14.The CDC recommend cleaning and disinfection of high-touch surfaces daily in household common areas: eg tables, hard-backed chairs, doorknobs, light switches, remotes, handles, desks, toilets, sinks. Lastly, exposure to natural sunlight,the use of antimicrobial copper surfaces, the application of a modified antimicrobial coating on surfaces and sensor taps and no door handles may be effective supplements to standard hygiene practices and present additional opportunities for controlling the transmission of COVID-19 from contaminated fomites.