Airborne droplets and contact routes transmit coronavirus. Airborne respiratory aerosol particles remain infectious for more than 3 hours. Australian scientists have investigated how SARS-CoV-2 is transmitted by contact with infected objects — fomites.

Household items such as mobile phone touch screens, ATMs, airport check-in counters, and self-service checkout counters in supermarkets usually become fomites. That the virus entered the body, it is enough to touch an infected object and then touching your eyes, nose, or mouth. The probability of getting sick after contact with fomite is 33%. That is why, to counter the spread of the coronavirus, who and national health systems recommend washing your hands with soap.

Australian scientists measured how long the SARS-CoV-2 virus lives on various surfaces: polymer banknotes, paper banknotes, brushed stainless steel, glass, vinyl, and cotton fabric. In a highly secure laboratory, scientists infected pre-disinfected surfaces with the virus. Since SARS-CoV-2 is rapidly inactivated under artificial sunlight, the experiment was performed in the dark. The relative humidity of the environment during the investigation is 50%. Scientists have observed how the survival rate of the virus changes depending on the surface and ambient temperature.

At 20°C, the SARS-CoV-2 virus was still detected on all non-porous surfaces: glass, polymer banknotes, stainless steel, vinyl, and paper banknotes after 28 days. On a porous material (cotton fabric) — after 14 days. The time required to kill 90% of the virus ranged from 5.5 days for cotton to 9.1 days for paper banknotes.

At 30°C, the coronavirus was detected on stainless steel, polymer banknotes, and glass for 7 days, and on vinyl and cotton fabric for 3 days. SARS-CoV-2 lived on paper banknotes for 21 days. 90% of the virus was destroyed from 1.4 days for vinyl to 4.9 days for paper banknotes.

At 40°C, the virus’s survival rate was significantly reduced compared to experiments at 20 and 30 °C — the virus died within a few hours. The time required to kill 90% of the virus ranged from 5 hours for polymer banknotes to 10.5 hours for vinyl.

Surface D value – a time required to kill 90% of the virus | half-life Temperature changes needed to change the D value by a factor of 10 – in °C
20 °C — days 30 °C — days 40 °C – hours
Stainless steel 5,96 | 1,80 1,74 | 12,6h 4,86 | 1,5 13,62
Polymer banknotes 6,85 | 2,06 2,04 | 14,7h 4,78 | 1,4 13,02
Paper banknotes 9,13 | 2,74 4,32 | 32,7h 5,39 | 1,6 12,43
Glass 6,32 | 1,90 1,45 | 10,5h 6,55 | 2,0 14,65
Cotton 5,57 | 1,68 1,65 | 11,0h 18,91
Vynyl 6,34 | 1,91 1,40 | 10,1h 9,90 | 3,0 16,86

On hospital personal protective equipment, SARS-CoV-2 remains viable for 21 days on both plastic and N95 mask when stored at room temperature.

SARS-CoV-2 is exceptionally stable on stainless steel surfaces at room temperature.

The stability of the virus on paper and polymer currency is of particular importance, as it determines the possibility of transmission of a viable virus both between people and between countries.

After 1 hour of drying at room temperature, the concentration of coronavirus on cotton fabric becomes 99% lower than after the same time on non-porous surfaces. That may be due to the virus sticking to the tissue fibers.

An important discovery is the coronavirus’s survival rate on glass surfaces — touch-screen devices such as mobile phones, ATMs, self-service checkout counters in supermarkets, and airport check-in counters. These surfaces are significantly frequently touched, but they are not subject to regular cleaning and therefore pose a risk of SARS-CoV-2 transmission. The situation is the same with mobile phones. A British study has shown that mobile phones may contain pathogens responsible for the hospital-acquired transmission of infections. Therefore, touch-screen devices should be regularly disinfected, especially if a large number of people touch them.

The coronavirus remains contagious for a much longer time than is generally considered possible. SARS-CoV-2 is detected on non-porous surfaces for at least 28 days at room temperature (20°C) and 50% relative humidity. Increasing the temperature while maintaining humidity reduces the coronavirus’s survival rate by up to 24 hours at 40°C. Applying these results to public health and transportation areas will reduce the risk of infection and prevent the spread of COVID-19.

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