22 April 2020

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COVID-19 emergency: Comparison between SARS-CoV-2 and SARS-CoV-1 on Aerosol and different Surfaces Stability

Authors: L. Breschi, S. Chirico

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A tough battle is being fought all over the world against Covid-19 emergency. The numbers are really worrying, because of the high contagion power of the virus.
Focusing on the dental aspect, as established in several scientific studies, dentists are the category most at risk of contagion, due to the ability of the coronavirus to remain in aerosol and on various surfaces.
In particular, this aspect was examined in the study published in "The New England Journal of Medicine", in which the authors compared the stability of SARS-CoV-2 virus (virus of the current pandemic) and SARS- CoV-1 (responsible for the epidemic in 2003) in five environments: aerosols, plastic, stainless steel, copper, and cardboard.
Here are the results of the various samples:
- Aerosol: SARS-CoV-2 remained viable in aerosols for 3 hours, with a reduction in infectious titer from 103.5 to 102.7 TCID50 per liter of air.  SARS-CoV-1 had a similar reduction, from 104.3 to 103.5 TCID50 per milliliter.
- Plastic: SARS-CoV-2 was detected up to 72 hours after application to these surfaces, but the virus titer was greatly reduced, from 103.7 to 100.6 TCID50 per milliliter of medium after 72 hours. The stability kinetics of SARS-CoV-1 were similar, from 103.4 to 100.7 TCID50 per milliliter.
- Stainless steel: SARS-CoV-2 was detected up to 48 hours after application to these surfaces, but the virus titer was greatly reduced, from 103.7 to 100.6 TCID50 per milliliter of medium. The stability kinetics of SARS-CoV-1 were similar, from 103.6 to 100.6 TCID50 per milliliter.
- Copper: no viable SARS-CoV-2 was measured after 4 hours and no viable SARS-CoV-1 was measured after 8 hours.
- Cardboard: no viable SARS-CoV-2 was measured after 24 hours and no viable SARS-CoV-1 was measured after 8 hours

Conclusion
Both viruses had an exponential decay in virus titer across all experimental conditions.
The half-lives of SARS-CoV-2 and SARS-CoV-1 were similar in aerosols, plastic and stainless steel. Instead, on cardboard, the half-life of SARS-CoV-2 was longer than that of SARS-CoV-1. The longest viability of both viruses was on stainless steel and plastic.
This indicates that differences in the epidemiologic characteristics of these viruses probably arise from other factors, including high viral loads in the upper respiratory tract and the potential for persons infected with SARS-CoV-2 to shed and transmit the virus while asymptomatic.

For additional information: Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1