Yes, cash can transmit the flu.
In an interesting report (via Well), it’s noted that the flu, including the H1N1 virus, can last for as long as an hour on money and other forms of paper currency. Worse, “mix in some human nasal mucus, and the potential for the virus to hang on long enough to find a victim increases, according to one of the few scientific studies done on flu transmission through cash.”
Mucous that’s left on cash “protects” the virus, causing it to persist for up to 17 days.
So, other than relying on coins, installing ATMs that sterilize money, or using credit cards more frequently, what can you do?
I’d wash my hands pretty much every time after handling cash. Or, as SmartMoney puts it, stop spending money.