#15,896
Long time readers will recall that nearly 14 years ago, during the summer of 2007 (see Infected Money: Nothing to Sneeze At), we looked at a report by Helen Branswell on a European study that found that influenza viruses could survive on - and be potentially transmitted by - contaminated banknotes and coins.
While influenza (and other respiratory viruses like COVID-19) are primarily transmitted by large droplets and/or aerosols, fomites - any surface that can be contaminated with a virus, bacteria, or fungi, and then later transfer that pathogen on to another - are a concern.
Exactly how big of a concern has been a subject of considerable debate, as most studies have been done under laboratory - not real world - conditions. But fomite transmission is likely responsible for some percentage of infections from influenza and/or COVID-19 (see EID Journal: Prolonged Infectivity of SARS-CoV-2 in Fomites).
Money is problematic in that it is normally kept in a wallet or a cash register - protected from sunlight and UV rays - and also protected from the drying effects of the air. It can pass from hand-to-hand several times a day. It isn't stationary, and so it is plausible that it could be an effective vector for a virus like COVID or flu.
As a result, during the 2009 H1N1 pandemic - and more recently during the COVID pandemic - retailers have been encouraging electronic transactions, and banks have been sanitizing, quarantining, or destroying potentially contaminated banknotes (see Reuters Fed quarantines U.S. dollars repatriated from Asia on coronavirus caution and CBS News Paper money shunned due to coronavirus).
A year later, and some researchers are starting to question just how important fomites are in the transmission of SARS-CoV-2, including in this January 2021 feature from Nature.com (see COVID-19 rarely spreads through surfaces. So why are we still deep cleaning?).
While I won't be giving up my hand sanitizer, or stop disinfecting the handles of shopping carts and doorknobs anytime soon, we've a new study - not yet peer reviewed - that suggests that concerns over contaminated money may be overblown.
The full (32-page PDF) is well worth reading, and while somewhat reassuring, there are some caveats.
Their experiments were done on European banknotes and coins - which may differ in composition and finish from others - and they used both SARS-COV-2 and BCoV (bovine coronavirus, as a surrogate with lower biosafety restrictions) - in their tests. Additionally, results from these two viruses may differ from what might be observed with other viruses, like influenza, adenoviruses, etc.
I've only posted the abstract and a couple of snippets from the report. Follow the link to read it in its entirety.
A realistic touch-transfer method reveals low risk of transmission for SARS-CoV-2 by contaminated coins and bank notes
Daniel Todt, Toni Luise Meister, Barbora Tamele, John Howes, Dajana Paulmann, Britta Becker, Florian H. Brill, Mark Wind, Jack Schijven, Baxolele Mhlekude, Christine Goffinet, Adalbert Krawczyk, Joerg Steinmann, Stepanie Pfaender, Yannick Brueggemann, Eike Steinmann
doi: https://doi.org/10.1101/2021.04.02.438182
This article is a preprint and has not been certified by peer review [what does this mean?].
Preview PDF
Abstract
The current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has created a significant threat to global health. While respiratory aerosols or droplets are considered as the main route of human-to-human transmission, secretions expelled by infected individuals can also contaminate surfaces and objects, potentially creating the risk of fomite-based transmission. Consequently, frequently touched objects such as paper currency and coins have been suspected as a potential transmission vehicle.To assess the risk of SARS-CoV-2 transmission by banknotes and coins, we examined the stability of SARS-CoV-2 and bovine coronavirus (BCoV), as surrogate with lower biosafety restrictions, on these different means of payment and developed a touch transfer method to examine transfer efficiency from contaminated surfaces to skin.Although we observed prolonged virus stability, our results, including a novel touch transfer method, indicate that the transmission of SARS-CoV-2 via contaminated coins and banknotes is unlikely and requires high viral loads and a timely order of specific events.
Competing Interest Statement
DT and ES receive consulting fees from the European Central Bank. FHB is executive partner of Dr. Brill + Partner GmbH. DP and BB are employees at Dr. Brill + Partner GmbH. BT and JH are employees at the European Central Bank. MW is employee at De Nederlandsche Bank.
(SNIP)
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. doorbell, shopping carts). The role of a contagious person contaminating banknotes and coins afresh when handing over, needs to be addressed in future studies.
Current government regulations to wear masks minimize the spread of exhaled droplets and aerosols, and in combination with good hand hygiene also mitigate the risk of transmission via contaminated surfaces.
Still, contamination of cash is most likely to occur indirectly by transfer from the hands of an infected person or finger contact with a contaminated surface. However, any contamination by these routes would likely result in a much lower degree of surface contamination than by direct contamination as investigated in this study.
Consequently, the overall chance of transmission of SARS-CoV-2 through banknotes, coins and credit/debit cards seems low since a timely order of specific events – sufficient viable virus deposited on a surface, survival of the virus until the surface is touched, and transfer of an infectious dose of virus – is required.
