April 16, 2020

expert reaction to unpublished conference abstract on European coins, banknotes and microbes

A conference abstract, press released from the European Congress on Clinical Microbiology and Infectious Diseases (ECCMID) conference, reports on European coins, banknotes and microbes.

Dr Graham Wheeler, Medical Statistician, UCL, said:

“This study looked at whether bacteria survived on different Euro coins or banknotes.  Whether the findings from this work apply to viruses too was not explored.

“The results presented do not fully state how the number of bacteria found on coins compare to the control surface (ceramic tile).  Similarly, the change in viable bacteria numbers on the 5 euro banknote after 24 hours are not reported.

“The authors are careful to mention that some bacteria were still present after 24 hours on all surfaces, so handling of coins and banknotes could still present opportunities for bacteria to be transmitted from one person to another.

“This study has not been peer-reviewed, so all findings should be interpreted with caution.”

Dr Simon Clarke, Associate Professor in Cellular Microbiology, University of Reading, said:

“It’s well documented that metal surfaces can kill bacteria, so it’s unsurprising that metal coins can do the same thing.  In this study, there has been no examination of the effects on viruses, which are entirely different things from bacteria.  These findings cannot be extended to the coronavirus causing CoViD-19.”

Prof Kevin McConway, Emeritus Professor of Applied Statistics, The Open University, said:

“This research sounds potentially interesting, but we’ve got so few details that it’s hard to assess its quality and importance.  All we have is a brief press release and a brief abstract of the paper that would have been presented at the conference.  In such a short space, only sketchy details can be given.  The research has not yet been peer reviewed by other scientists.

“The number of repeated experiments with each of the microbes was not very large (4 for one of the microbes, 5 for the other).  We aren’t told much about the variability of the results from these separate experiments, which may be relevant to the statistical interpretation.

“And a very important (non-statistical) point at the present time is that the micro-organisms involved were two different bacteria, and not a virus, so the findings tell us nothing practical about how a virus such as SARS-CoV-2 might survive on coins or banknotes.”

The abstract ‘Take care of the cents and the euros look after themselves? Antimicrobial activity of European money’ by Johannes K. Knobloch et al. has been press released from the European Congress on Clinical Microbiology and Infectious Diseases (ECCMID) conference. There is no paper and this is not peer-reviewed.

Declared interests

Prof Kevin McConway: “Prof McConway is a member of the SMC Advisory Committee, but his quote above is in his capacity as a professional statistician.”

None others received.