Droplet infections play a major role in the transmission of the Coronavirus. Yet, we must not forget about the risk of touching contaminated surfaces and objects. What do we know at this point?
By Mohamed A. Deyab
Coronaviruses, such as the currently spreading SARS-CoV-2, cause dangerous respiratory tract infections in humans. Aside from a transmission via respiratory droplets, an infection can also happen via direct and indirect contact with surfaces and objects.
In a review article, recently published in Zeitschrift für Naturforschung C, Mohamed A. Deyab addresses essential questions and answers related to coronaviruses’ activities on inanimate surfaces. The main questions are: Does the type of inanimate surface affect the activity of coronaviruses, and what are the most suitable substances that can be used to inactivate viruses?
Coronaviruses don’t like it hot and dry
A number of researchers have already examined the survival of different coronaviruses on various surfaces. One study found that the Human coronavirus 229E (HCoV-229E) remained active on glass surfaces, Teflon, ceramic tiles, silicon rubber and stainless steel for three to five days (under controlled conditions at 21°C and a humidity of 30% to 40%).
Furthermore, two types of Coronavirus (HCoV-229E and HCoV-OC43) were found to persist longer in a wet than a dry environment. In an aqueous suspension, they remained active for three to five days. After drying, however, they became undetectable after just a few hours. The review also mentions that the SARS Coronavirus remains active in serum and urine for 96 h and 72 h, respectively.
Generally, environmental conditions such as temperature and relative humidity are said to have a high impact on the persistence of coronaviruses on surfaces. Studies have found the best conditions for an inactivation of coronaviruses to be at a humidity of 50% and at high temperatures of over 40 °C.
The review furthermore specifically mentions copper alloy, which can destroy (corona-) viruses within a few minutes. For this reason, the material is increasingly used in healthcare facilities, e.g. on door handles or handrails. Other substances that are effective in the elimination of coronaviruses are, for example, chloroxylenol and povidone-iodine (both common ingredients of household disinfectants and wound cleaners) but also pine oil.
Further studies to inform future practice – especially in the context of COVID-19 – are now required, M.A. Deyab concludes in his review.
If you are interested, learn more in the corresponding review article: