In the last newsletter on coronavirus (COVID-19), the recommended precautionary measures to avoid or reduce the spread of infection were described.
First and foremost are the measures that need to be taken to restrict transmission via the respiratory tract or hands. Infection via the respiratory tract comes from inhaling particles excreted and exhaled from an infected person’s respiratory tract, and these are inhaled by an uninfected person who is within close proximity to that person. Infection via the hand comes from touching a surface that has been contaminated with the virus, then touching your mouth, nose or eyes, all frequent, subconscious habits. Infection via the eye is common as the virus gains entry via the conjunctiva. Transmission of COVID-19 is more frequent through person-to-person via secretions of the respiratory tract.
Most important is the droplet transmission of the virus released in respiratory tract secretions. Thus, the highest risk of spreading infection arises when an infected person sneezes or coughs, but also if you have a conversation within short distance, you can infect another person or be infected yourself. The infection can also be transmitted if you touch an infected surface and then carry the infection on as described above.
Droplets typically do not fly more than about two meters and do not remain airborne for longer; however, some researchers have described COVID-19 (SARS-CoV-2)as remaining in an aerosol formunder experimental conditions for at least three hours (van Doremalen N, et al. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. N Engl J Med. 2020 Mar 17. doi: 10.1056/NEJMc2004973)
Therefore regular and thorough handwashing with soap, or with an alcohol-based hand sanitiser (minimum concentration 62% ethanol or isopropanol) and mouth-nose protection masks (the best are the special virus mask) and maintaining a two metre distance between people are an important part of prevention. Regular surface disinfection is still a vital and necessary safety measure.
There is a question of how long the virus remains infectious on such surfaces and what must be disinfected with.So far, while it is believed that you can become contaminated by the virus by touching inanimate objects (doors, handrails, etc.) which have respiratory tract secretions on them (someone has sneezed into their cupped hands, and then opened a door) and then touching your mouth, nose, etc., it has not been sufficiently documented whether COVID-19 is transmitted via such inanimate surfaces or how long inanimate surfaces may remain infectious if contaminated, under varying conditions.
It is known from other human pathogenic corona viruses that they can survive for a certain time on inanimate surfaces such as metal, glass or plastic. The survival time depends on other influencing factors such as ambient temperature and air humidity. For example, while in one study a Corona variant (HCoV-229E) on plastic lost its infectivity after 72 hours,SARS-CoV-1 remained infectious on the same medium for up to six days*. Due to the structural similarity of SARS-CoV-1 and SARS-CoV-2 (COVID 19) a similar transferability over such areas could be expected (Robert Koch Institute RKI).
*Some sources report up to 9 days.
On other surfaces that are more difficult to disinfect (e.g. clothing), it is not clear how long the virus can survive there. It can be assumed that the viruses will dry out faster and therefore become inactive more swiftly.
Surface disinfectants with proven virucide properties are suitable for inactivation, such as alcohol-based disinfectants.
Sources of information and recommendations: experts from the Harvard School of Public Health, Robert Koch Institute and WHO; and scientific groups (research).
Prof. Dr. Werner Seebauer is Dean of Studies – Association of German Preventologists, Head of Preventive Medicine Department of Institute of Transcultural Health Sciences (European University Viadrina) and Head of Preventive Medicine – NESA (The New European Surgical Academy). Since 2000, prof. dr. Werner Seebauer worked only in preventive medicine, after ten years spent at the Frankfurt University Hospital. He is also involved in the medical professionals training for nutrition and prevention.