There’s a natural inclination to think “ew” when presented with a foreign, used bar of soap. Someone else’s germs might be on that, right?! Wrong, according to Juliet Morrison, PhD, assistant professor at University of California Riverside’s Department of Microbiology and Plant Pathology, whose research focuses on immunological and virological methods.
The Centers for Disease Control and Prevention (CDC) recommendation about not sharing personal items (including bar soap) is referencing methicillin-resistant staphylococcus, also known as MRSA, a type of staph infection that is resistant to certain types of antibiotics, “which is a bacterium,” says Dr. Morrison. “Bacteria are much more hardy than viruses, especially enveloped viruses like SARS-CoV-2,” (i.e., COVID).
If you’re concerned about MRSA, that’s one thing—but when it comes to contagious viruses like COVID, Dr. Morrison says you should be fine. It’s super unlikely that it would remain on a bar of soap; she says bar soap is arguably just as safe as liquid soap in a shared environment.
“The CDC guidance makes sense when talking about MRSA, but I don’t think this guidance is best for viruses,” she says. “Though there is a tiny possibility that an enveloped virus could remain intact on a bar of soap, once the bar of soap is rubbed with water to produce a lather, the viral envelope would be disrupted by the detergent particles, and the virus would no longer be infectious. The key is to have a good lather going.”
In fact, in the case of COVID or another virus, Dr. Morrison explains that the infected person would have to cough into their hand and then touch a bar of soap—and then not lather the soap to spread bacteria (see what we mean by unlikely?).
“Such high viral loads on a bar of soap are very unlikely,” she says, but—“If people are worried about this minute risk, I would suggest using liquid soap, and sanitizing the pump of the soap dispenser before and after each use if the pump comes into direct contact with people’s hands.”
For some people, the stress of even that tiny possibility of infection might be damaging in and of itself; in that case, follow Dr. Morrison’s advice: Get a liquid soap with a pump. Or, keep your soap to yourself in a personal caddy if you’re in a shared bathroom. Otherwise, you should be fine… it is soap, after all!