Catch Me if You Can – ECB Reports on Cash and COVID

A new report published last month – ‘Catch Me (If You Can): Assessing the Risk of SARS-CoV-2 Transmission via Euro Cash’ – by the European Central Bank (ECB) sought to answer key questions such as, how long do coronaviruses remain infectious on banknotes and coins? Is it possible to become infected through contact with cash?

This Occasional Paper Series, written in collaboration with the Department of Medical and Molecular Virology at Ruhr-Universitat Bochum, concluded that the risk is minimal.

The report was conducted and presented in two parts. First, it looked at how demand for, and use of, euro cash changed during the pandemic, to provide context. Second, it dispelled concerns about contacting the virus from cash transactions.

Developments in cash circulation

The circulation of euro banknotes has increased strongly since its introduction, but the growth rate during crises, most notably the Lehman Brothers crisis and now the COVID-19 pandemic, has been extraordinarily high.

Euro banknote circulation from 2008-2021.

However, the growth rate during COVID-19 has some special features. The annual growth to February 2020 – the last month before the pandemic spread throughout Europe – was 12%, taking the total value of euro banknotes in circulation to €1.435 billion. This contrasts with roughly a 5% average annual growth rate in equivalent periods in the five years prior to the pandemic. The annual growth rate did slow in March and April (2021) to 10% and 9% respectively, still much higher than normal, taking the total banknotes in circulation to €1.455 billion.

The authors point out that the gap between banknote circulation growth in normal times and during this pandemic has also been observed for other currencies too. But whilst in most crises the increase in circulation is mainly driven by higher banknote withdrawals and hence higher gross issuance, during the pandemic it has been different.

Despite an increase in March 2020 at the start of the pandemic, the value of banknotes issued (outflows from the ECB) during the year fluctuated at around 70-90% of the average level for the previous five years. However, the value of banknotes returned (inflow to the ECB) decreased even further – to around 60-80% of normal levels.

Banknote flows in 2020-21 set against flows in the previous five (non-crisis) years.

The stronger decline in the value of returned notes compared with the value of notes issued resulted in the higher overall circulation. This counterintuitive combination of weakened banknote flows and a strong increase in overall cash demand indicates the uniqueness of this crisis.

The explanation of this is based on the acceptance that the demand for cash has three differentiated components – 1) transactional demand in the euro area, 2) store of value demand in the euro area, and 3) foreign demand.

Hence reduced cash operational activity in the ECB, mostly associated with diminished use of cash for daily transactions, is compatible with an overall increase in demand for cash if either store of value in the euro area or foreign demand, or both, experienced a notable increase.

Although estimates for the different demand components for 2020 during the pandemic were not available, the authors concluded it is likely that the increase in circulation was mainly driven by store of value demand in the euro area. This conclusion was reached because ECB data showed that net shipments of euro banknotes to countries outside of Europe decreased and it was safe to assume that informal channels, such as tourism and flights, did not play an important role due to the pandemic restricting both.

Euro coin circulation

Euro coins represent a smaller portion of the cash in circulation, accounting for around 2% of the total in terms of value. Over the last 10 years, the value of euro coins in circulation has increased by an average of approximately 3.5% each year, reaching €30 billion at the end of 2020. In February 2021 coin circulation increased by only 1.6% year-on-year, a far slower growth rate than for banknotes and consistent in that coins in circulation have not been affected in previous crises.

However, it was noted that there had been a significant decrease in the value of coins issued and returned since the start of the pandemic, the most significant decline being recorded in April 2020, when returns were 47% of the average of a non-crisis year. The difference in flows was thought to be attributable to limited shopping and travel opportunities.

Coins flows (issued to and returned by the public) compared with the average of those of the five previous (non-crisis) years (2015-2019).

The main difference from the banknote situation is that the value of coins returned did not decrease significantly more than that of coins issued, indicating that the growth in circulation was not as large as that of banknotes. The explanation given was that although both banknotes and coins are used for transactions, coins are rarely used as a store of value.

Survey evidence for reduced use of euro cash

To shed light on the extent of the change of transactional demand for cash during the pandemic, in July 2020 the ECB carried out a small-scope euro area survey on the impact of the pandemic on cash trends. It indicated that the use of cash for transactions had decreased; although around half of the respondents reported using cash as frequently as before the pandemic, 40% reported using cash somewhat less or much less often.

Reasons (by percentage) why IMPACT survey respondents are using less cash (Source: European Central Bank).

This decline in the use of cash for transactions was matched by more frequent use of card payments – 30% of respondents reported an increase in PIN or signature card usage but 40% reported increased contactless card usage, confirming an acceleration of the pre-COVID trend.

The group of respondents using cash less often were also asked about their expected behaviour after the pandemic. A significant majority (87%) said they would most likely use cash less, but further evidence would be needed to support this.

The respondents were also asked for reasons why they were paying less with cash. The increased convenience of electronic payments was the main reason (48%), followed by the risk of infection of the virus by the banknotes (38%), the latter varying depending on the demographic group – higher education levels (42%) showing greater concern than those with secondary (36%) or primary (33%) education.

Also, respondents living in urban areas reported greater concern regarding infection (40%) than those living in rural areas (35%). Notably, 20% said the places where they usually shopped either no longer accepted cash or strongly advised against it. However, 52% of respondents still considered the option to pay in cash to be important or very important, the fear of infection seemingly not influencing this view.

In reviewing the overall survey population – ie. those both using and not using cash – 30% of citizens were fairly concerned about the risk of contracting the virus from banknotes, and 11% were very concerned.

Laboratory evidence dispels concerns

In order to establish whether the fear of contracting the virus from euro banknotes and coins is justified, research was conducted by the ECB with independent laboratories and universities, principally the Ruhr-Universitat Bochum, in 2020-21.

The research programme included testing the survivability of SARS-CoV-2 and surrogate viruses on banknote and coin surfaces until no virus was detectable, plus a new method to investigate transferability from banknotes and coin surfaces to human fingers (number of virus particles transferred from surface to finger).

The combination of both aspects – survivability and transferability – are considered key to determining the risk of transmission via euro cash.

Survivability

A €10 banknote was used for the tests, mainly because it is widely used in transactions and is distinctive for being coated with a varnish to protect its surface and prolong its lifetime in circulation.

5 cent, 10 cent and 1 euro coins were tested as these covered the different euro coin alloys. A stainless steel carrier was used as a reference material.

Droplets of a liquid containing controlled amounts of the virus were placed on the surface of samples and left untouched for predefined periods (eg .15 minutes, one hour, two days). Two different quantities of virus were used for each period – a typical laboratory quantity considered to be very high and not representative of real-life conditions, and a lower load considered to be more representative of real-life conditions. The quantity of virus still surviving at the end of each period was determined.

The virus survived longest on stainless steel – some viable virus could persist for up to seven days. On the €10 banknote, some virus was detectable for up to 72 hours, on the 5 cent coin for 30 minutes, the 10 cent coin for six hours and the 1 euro coin for 24 hours.

The fast decay in the 5 cent coin can be attributed to its copper plating, and for the 10 cent and 1 euro coins the presence of copper in the coin alloy plays a certain antiviral role too.

For the €10 note, the virus decreased 10,000 times close to the detection limit in 72 hours. This could be attributed to the porous nature of the banknote material into which the viruses may penetrate – the report noting that the risk of contamination mainly arises from the surface of a banknote, if at all.

The question arises, even if the virus survives for these indicated periods on the surface of the stainless steel coins and €10 banknote, can it be transferred first onto human skin (fingers) and then from the hand to reach the mucosal routes?

Transferability

The question posed was how much of the remaining virus after different periods could be transferred from a contaminated banknote or coin to a human being via fingers, and could this quantity be enough to be infectious?

To establish this, new tests implementing a new protocol to study touch-transfer efficiency between fomites and skin were organised and conducted in two different laboratories according to slightly different test protocols. The two viral loads used in the survivability tests – high and lower (more realistic) – were also used in these tests.

The tests were conducted in two conditions – wet, immediately after the virus droplets were applied to the test surfaces, and dry, ie. after the visible drying of the inoculum on the surfaces (30 minutes on the banknote and up to one hour on the 10 cent coin, PVC and stainless steel).

For both viral loads, the results showed a significant transfer from all surfaces studied in the wet status – representing a situation where a person adds the virus to the test surface and which is then touched by another person. In real life this situation would be rare as it is not expected that someone would touch a banknote or coin with wet materials on its surface.

The dry status offered a more realistic situation and should be the one considered when drawing conclusions about the risk of the SARS-CoV-2 virus being transmitted by touching surfaces.

For the high viral load, the transfer of SARS-CoV-2 from the €10 banknote is greatly reduced and for the 10 cent coin is below the detection limit. For the more realistic lower viral load, the virus remaining on the surface of the €10 banknote and 10 cent coin after drying is below the detection limit. Only from the PVC could low amounts of infectious virus be recovered.

Test conclusions

The results of the stability tests show that, when a high viral load is applied, the virus can survive on banknote and coin surfaces for up to several days, albeit at very low levels.

The novel transferability testing results show that the virus is only transferred from cash to human finger in very low quantities – below what would be needed to be infectious, making the risk of infection very low.

However, it is generally accepted that the high viral load does not fully replicate the real-life situation, whereas the lower viral load is thought to better replicate it. The results for the lower viral load indicate a much lower risk of infection, which becomes negligible after the virus has dried.

Finally, there is growing evidence that the most significant contributor to the spread of COVID-19 between people is via respiratory fluids and the air (aerosol transmission).

The ECB report concluded that based on its test results, recent scientific literature on transferability and also the ECB’s previous findings on the avian flu and swine flu viruses, the risk of transmission via banknotes and coins is very low and cash is safe to use.

Final thought

The pandemic has seen much ‘bad science’ both carried out and used to justify a movement against the use of cash. The research used in this study is thorough, measured and rigorous. The result is a persuasive conclusion that the risk of infection from banknotes and coins is extremely low, below that of many other day-to-day objects encountered in public spaces.

The full report can be viewed at www.ecb.europa.eu/pub/pdf/scpops/ecb.op259~33b180d450.en.pdf.