A new study looking at how long the novel coronavirus can survive on surfaces found that it can remain infectious on some surfaces — including bank notes — for at least 28 days, provided the temperature is right.
Published this week in the Virology Journal, the new paper describes how researchers tested the virus on several surfaces, including cotton and bank notes, at numerous temperatures in order to measure the lifespan of the virus under these different circumstances.
They found that the virus dies significantly faster on surfaces in hotter temperatures, and can survive on several non-porous surfaces for up to four weeks — much longer than previous studies have indicated.
Overwhelmingly, evidence has shown that the primary way COVID-19 is spread is through droplets and through sharing air with others, but that hasn’t stopped the fear of surface transmission. Hand washing is still one of the most important prevention methods that health officials tout.
Previous studies have looked at how long SARS-CoV-2, the virus that causes COVID-19, remains infectious on different surfaces, with some studies finding it to be a matter of hours, and others saying it could be days.
In this study, the surfaces researchers tested the virus on included Australian bank notes — which, like Canadian bank notes, are polymer — paper bank notes, glass, vinyl, stainless steel and cotton.
Researchers noted that they wanted to include money because it is an object that travels frequently between different people. Stainless steel, vinyl and glass are materials found in most public spaces, and cotton is often found in clothing and bedding.
When a virus gets onto a surface, it is often through a sneeze or through droplets expelled from the mouth. Researchers diluted SARS-CoV-2 “in a defined organic matrix […] designed to mimic the composition of body secretions” before placing it onto the materials to measure the longevity.
They noted in the paper that the concentration of the virus in each sample was high, it still “represents a plausible amount of virus that may be deposited on a surface.”
Samples of each material with the virus on it were placed into a “humidified climate chamber” so a set humidity of 50 per cent relative humidity could be maintained while the samples were tested at different temperatures and timeframes.
Samples were tested at 20, 30 and 40 degrees Celsius, and were inspected 1 hour, 3 days, 7 days, 14 days, 21 days and 28 days after the virus had first been introduced to the material.
Researchers found that at 20 degrees Celsius, the virus could survive for at least 28 days on every material except for cotton, the most porous of the materials tested.
Read more: CTV News