[nudephil (OP)]

James asks:

Which method of payment would have a higher risk of spreading the virus: a debit card or cash?

What do we think?

[alancalverd]

Copper has reported antiviral properties, so coins are likely to be reasonably safe from persistent infection and of course can be easily disinfected with alcohol, hypochlorite, ultraviolet or ozone - even soapy water. Cards are not inherently antiviral and are rather more prone to chemical damage. Banknotes are remarkably resilient but clearly prone to chemical damage and retention of grease- or water-borne infection. 

[hamdani yusuf]

You should also account for the frequency and traceability of contact. The card can only get the virus from your own transactions, while the cash can get it from anyone else's transactions before you.