Even if you’re not usually a germaphobe, cold and flu season can have the strongest-willed of us feeling squeamish about touching things like bus and subway poles, doorknobs, and even shaking a stranger’s hand. As many moms like to remind their kids: You don’t know where that hand has been. And during the colder months, when it seems that everyone is sniffling and sneezing, a hands-off policy may seem smart.

But how likely is it really that you’d get sick from touching an infected handrail or countertop?

Pretty likely, Alison Carey, MD, an associate professor of microbiology and immunology at Drexel University, tells Health. “Flu viruses can survive on hard surfaces (like bus poles) and infect another person for 24 to 48 hours,” she says. “Cold viruses don’t survive as long—usually a few hours. But there is evidence that they can survive and be passed on for up to 24 hours.”