I have read that the Covid 19 Coronavirus, can live for up to three days on non sanitised hard surfaces. If therefore, someone who unknowingly has the virus, handles their credit card and transfers the virus to their credit card. On making a purchase the virus is then transferred to the card reader in the shop. It therefore seems logical that every person who subsequently touches the card reader, with their own credit card, collects the virus from the card reader, on to their own credit card and takes it home to share with family and friends. Please check on Google, as to how long the virus can survive on various surfaces.It will shock you Very interested in any comments.