Study Shows Coronavirus is Unlikely to Spread via Cash
Aug 9, 2021
A study that realistically models touch-transfer of SARS-CoV-2 via banknotes and coins has concluded the virus is unlikely to be spread by cash, with other frequently-touched surfaces being higher risk, and respiratory droplets in the air remaining the primary route of transmission.
In collaboration with the European Central Bank, researchers at Ruhr-University Bochum in Germany designed an experiment representing real world conditions as closely as possible, exploring how long the virus that causes COVID-19 could remain infectious on banknotes and coins.
The researchers open by saying that respiratory droplets and aerosols exhaled from infected individuals seem to present the greatest risk of infection, according to current evidence. Given these droplets can land on surfaces, and have been found to remain viable—thus potentially infectious—for days under controlled laboratory conditions, inanimate objects could also be a vector of transmission. Much has been made of the risk presented by cash, and the study sought to provide a realistic picture of how substantial this risk is.
Overall, our results point to a low risk of SARS-CoV-2 transmission by coins and banknotes and the tendency to prefer contactless payment over cash during the pandemic seems unnecessary.
According to the study, ‘infectious viruses have not been directly detected on banknotes or coins.’ The notion of cash having the potential to transmit SARS-CoV-2 was highlighted by observations of human influenza viruses that were able to survive on banknotes for up to three days when deposited in high concentrations, not representative of a typical contamination event, such as a cough or sneeze.
The new study found loss of infectivity was higher on banknotes and coins than on stainless steel, indicating more rapid desiccation due to liquid absorption (on notes) and antimicrobial surface properties (e.g. copper in coins). It also pointed to decay of SARS-CoV-2 being determined by a combination of the initial amount of infectious virus deposited on a surface, plus environmental factors such as temperature, humidity, light and UV conditions. Lower viral burdens that best mimicked real life contamination events—such as a cough—were not effectively transferred onto the surface of cash.
Given that cash is typically stored securely in wallets and purses, the risk of direct contamination through exhaled droplets and aerosols seems much lower than constantly exposed surfaces (e.g. doorbells, shopping carts).
The researchers conclude that current government regulations requiring the wearing of masks minimise the spread of exhaled droplets and aerosols. This—in combination with good hand hygiene—mitigates the risk of transmission via any contaminated surface.