Article: The effect of temperature on persistence of SARS-CoV-2 on common surfaces
Virology Journal 17, Article number: 145 (2020)
Published 07 October 2020
Shane Riddell, Sarah Goldie, Andrew Hill, Debbie Eagles and Trevor W. Drew
Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australian Centre for Disease Preparedness, Geelong, VIC, Australia
This study was supported by a SARS-CoV-2 collaboration grant from the Defence, Science and Technology Group (Australia).
The surfaces we touch every day (smart-phones, banknotes, steel railings on public staircases etc.) are theorised to spread SARS-CoV-2.
SARS-CoV-2 is the strain of coronavirus that causes COVID-19 disease. The current line of thought is that transmission of SARS-CoV-2 occurs mostly through particles or liquid droplets in the air.
Current evidence for infected surface (fomite) transmission of SARS-CoV-2 has shown some variation in results.
This study hoped to further investigate the longevity of SARS-CoV-2 on these surfaces at different temperatures.
SARS-CoV-2: Severe acute respiratory syndrome coronavirus 2 is a new strain of coronavirus that causes illness in humans with the ability to spread between people
COVID-19: Disease caused by SARS-CoV-2 that can lead to severe illness. Symptoms include dry cough, fever, sore throat, shortness of breath and loss of taste/smell
Aerosols: The tiny particles in the air that can be inhaled
Fomites: Surfaces that can be contaminated with a pathogen and spread to a new host through contact
Environmental stability: The way in which something survives in certain environmental conditions
SAR-CoV-2 was isolated, treated and suspended in an ASTM E2197 matrix (including serum albumin, tryptone and mucin) to resemble body secretions. The SARS-CoV-2 isolate used in this study was supplied by the Peter Doherty Institute on behalf of South Australian Health.
A range of common surfaces were sized into small ‘coupons’ of area 1-1.5cm2 including: polymer (plastic) and paper bank notes, stainless steel, glass, vinyl and cotton cloth. Each surface was sterilised and dried prior to being exposed to SARS-CoV-2.
10 microlitres of viral suspension was introduced into each surface coupon and incubated at three different temperatures of 20 °C, 30 °C and 40 °C. Humidity was kept constant at 50% and the incubation took place in darkness. The experiment lasted for up to 28 days in the 20 °C and 30 °C setups with sampling at a range of time intervals across the month. For the 40 °C setup, the experiment took place over 7 days.
The findings were statistically analysed.
At 20 °C: SARS-CoV-2 survived on all surfaces for at least 28 days except for cotton that was less than 14 days.
At 30 °C: SARS-CoV-2 lasted 21 days ** on paper banknotes, 7 days on glass, steel and plastic bank notes, and 3 days on cotton and vinyl.
At 40 °C: SARS-CoV-2 remained for 2 days on vinyl, 1 day on glass, steel, paper and plastic bank notes and less than 16 hours on cotton.
** A single well of virus was found on days 14 and 21, 99% of the virus was not infectious by day 7
These results show that SARS-CoV-2 has the ability to be infectious on every-day surfaces for long periods of time, up to one month in some cases. SARS-CoV-2 also appears to survive better at cooler temperatures and on smooth or non-porous surfaces like glass and steel.
SARS-CoV-2 is mostly transferred between people through the air. However, this study provides more evidence that the common surfaces we share could increase the risk of viral spread by acting as secondary routes of transmission. These surfaces such as glass, steel and plastic make up objects most people wouldn’t give a second thought to touching every day including mobile phone screens, bank notes or steel railing. The findings also provide insight into the temperature conditions that SARS-CoV-2 persists in. Understanding how SARS-CoV-2 spreads is critical when designing public health initiatives to try and suppress the spread of the virus.
Over the past year there has been significant efforts by research teams globally to learn more about SARS-CoV-2 and the disease it causes, COVID-19. The findings on cause, pathophysiology and drug trials are paving the way for novel therapeutic and prevention strategies. This study highlights that not all contributions to this mission need to involve extensive use of animals.
Although this study does not directly use any animals it was noted that serum with animal hosts was utilised to prepare the viral samples