Plastic or cash?  Where Covid viruses stick the longest

“At the beginning of the pandemic, there was a massive outcry that companies should stop using cash. All companies followed that advice and said, ‘OK, we’ll only pay with credit cards,'” said study author Richard Robison, professor of microbiology and molecular biology at Brigham Young University – a private Mormon university.

The research team collected a bunch of $1 bills, quarters, pennies and credit cards and “vaccinated” the money with SARS-CoV-2. The cash, coins and cards were then sampled and tested for virus detection at four time points: 30 minutes, four hours, 24 hours and 48 hours.

Difficult to see

The researchers found that SARS-CoV-2 was difficult to detect on the dollar bills, even 30 minutes after they were inserted. The study found the virus was reduced by 99.9993 percent after 30 minutes. In further tests after 24 and 48 hours, no live virus was found on the banknotes.

In contrast, the virus on cash cards was only 90 percent reduced after 30 minutes. Although this reduction rate increased to 99.6 percent after four hours and to 99.96 percent after 24 hours, the virus was still detectable on the money cards after 48 hours. The result for the coins was similar to that for the plastic cards: the virus presence initially fell sharply, but was still testing positive for the live virus after 24 and 48 hours.

Surprised

The researchers were surprised by the instability of the paper money bills (which in the US are made from a blend of 75 percent cotton and 25 percent linen): after applying 1 million viable virus particles to the bills, after 24 hours they could no longer detect any virus at all .

The research team also obtained fresh samples of $1 bills, quarters, and pennies from the BYU campus and from local restaurants to test for the virus. Within an hour of receiving the money, the researchers systematically wiped the surfaces and edges of the cash/coins with a sterile cotton swab. They also wiped a collection of cash cards. They detected no SARS-CoV-2 RNA on the banknotes or coins and only a small amount of the virus on the money cards.

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